Covariance & Correlation
|
|
- Cora Jacobs
- 7 years ago
- Views:
Transcription
1 Covarance & Correlaton The covarance between two varables s defned by: cov x,y= x x y y =xyxy Ths s the most useful thng they never tell you n most lab courses! Note that cov(x,x)=v(x). The correlaton coeffcent s a untless verson of the same thng: cov x,y = x y If x and y are ndependent varables (P(x,y) = P(x)P(y)), then cov x,y=dxdyp x,yxy dxdyp x,yx dxdyp x,yy =dxp xxdyp yy dxp xx dyp yy= 0 Physcs 509 9
2 More on Covarance Correlaton coeffcents for some smulated data sets. Note the bottom rght---whle ndependent varables must have zero correlaton, the reverse s not true! Correlaton s mportant because t s part of the error propagaton equaton, as we'll see. Physcs
3 Varance and Covarance of Lnear Combnatons of Varables Suppose we have two random varable X and Y (not necessarly ndependent), and that we know cov(x,y). Consder the lnear combnatons W=aX+bY and Z=cX+dY. It can be shown that cov(w,z)=cov(ax+by,cx+dy) = cov(ax,cx) + cov(ax,dy) + cov(by,cx) + cov(by,dy) = ac cov(x,x) + (ad + bc) cov(x,y) + bd cov(y,y) = ac V(X) + bd V(Y) + (ad+bc) cov(x,y) Specal case s V(X+Y): V(X+Y) = cov(x+y,x+y) = V(X) + V(Y) + cov(x,y) Very specal case: varance of the sum of ndependent random varables s the sum of ther ndvdual varances! Physcs
4 Gaussan Dstrbutons By far the most useful dstrbuton s the Gaussan (normal) dstrbuton: P x,= 1 1 x e Mean = µ, Varance=σ Note that wdth scales wth σ. Area out on tals s mportant---use lookup tables or cumulatve dstrbuton functon. In plot to left, red area (>σ) s.3%. 68.7% of area wthn ±1σ 95.45% of area wthn ±σ 99.73% of area wthn ±3σ 90% of area wthn ±1.645σ 95% of area wthn ±1.960σ 99% of area wthn ±.576σ Physcs 509 1
5 Why are Gaussan dstrbutons so crtcal? They occur very commonly---the reason s that the average of several ndependent random varables often approaches a Gaussan dstrbuton n the lmt of large N. Nce mathematcal propertes---nfntely dfferentable, symmetrc. Sum or dfference of two Gaussan varables s always tself Gaussan n ts dstrbuton. Many complcated formulas smplfy to lnear algebra, or even smpler, f all varables have Gaussan dstrbutons. Gaussan dstrbuton s often used as a shorthand for dscussng probabltes. A 5 sgma result means a result wth a chance probablty that s the same as the tal area of a unt Gaussan: 5 dtp t=0,=1 Ths way of speakng s used even for non-gaussan dstrbutons! Physcs
6 Why you should be very careful wth Gaussans.. The major danger of Gaussans s that they are overused. Although many dstrbutons are approxmately Gaussan, they often have long non-gaussan tals. Whle 99% of the tme a Gaussan dstrbuton wll correctly model your data, many foul-ups result from that other 1%. It's usually good practce to smulate your data to see f the dstrbutons of quanttes you thnk are Gaussan really follow a Gaussan dstrbuton. Common example: the rato of two numbers wth Gaussan dstrbutons s tself often not very Gaussan (although n certan lmts t may be). Physcs
7 Revew of covarances of jont PDFs Consder some multdmensonal PDF p(x 1... x n ). We defne the covarance between any two varables by: covx,x j =dxpx x x x j x j The set of all possble covarances defnes a covarance matrx, often denoted by V j. The dagonal elements of V j are the varances of the ndvdual varables, whle the off-dagonal elements are related to the correlaton coeffcents: n 1 n ]... n n n1 1 n n n... n =[ V 1 1 n j Physcs
8 Propertes of covarance matrces Covarance matrces always: are symmetrc and square are nvertble (very mportant requrement!) The most common use of a covarance matrx s to nvert t then use t to calculate a χ : = j y f x V j 1 y j f x j If the covarances are zero, then V j =δ j σ, and ths reduces to: = y f x Warnng: do NOT use the smplfed formula f data ponts are correlated! Physcs
9 Approxmatng the peak of a PDF wth a multdmensonal Gaussan Suppose we have some complcatedlookng PDF n D that has a well-defned peak. How mght we approxmate the shape of ths PDF around ts maxmum? Physcs 509 1
10 Taylor Seres expanson Consder a Taylor seres expanson of the logarthm of the PDF around ts maxmum at (x 0,y 0 ): logpx,y=p 0 Axx 0 Byy 0 Cxx 0 Dyy 0 Exx 0 yy 0... Snce we are expandng around the peak, then the frst dervatves must equal zero, so A=B=0. The remanng terms can be wrtten n matrx form: logpx,yp 0 x,y C D E x E y In order for (x 0,y 0 ) to be a maxmum of the PDF (and not a mnmum or saddle pont), the above matrx must be postve defnte, and therefore nvertble. Physcs
11 Taylor Seres expanson Let me now suggestvely denote the nverse of the above matrx by V j. It's a postve defnte matrx wth three parameters. In fact, I mght as well call these parameters σ x, σ y, and ρ. Exponentatng, we see that around ts peak the PDF can be approxmated by a multdmensonal Gaussan. The full formula, ncludng normalzaton, s Px,y= logpx,yp 0 x,y C D E x E y { 1 x y 1 exp 1 [ xx 0 1 x yy 0 y xx yy ]} 0 0 x y Ths s a good approxmaton as long as hgher order terms n Taylor seres are small. Physcs
12 Interpretaton of multdmensonal Gaussan Px,y= { 1 x y 1 exp 1 [ xx 0 1 x yy 0 y xx 0 x yy 0 y ]} Can I drectly relate the free parameters to the covarance matrx? Frst calculate P(x) by margnalzng over y: Pxexp{ 1 1 xx 0 x Pxexp{ 1 1 xx 0 x } } { dy exp 1 [ yy 0 1 y dy exp{ 1 [ yy 0 1 y xx 0 x yy 0 y ]} xx yy xx xx 0 x y x x Pxexp{ 1 xx } 0 dy 1 x exp{ 1 [ yy 0 1 y xx 0 xx 0 } x } x Pxexp{ 1 xx } 0 1 exp { xx 0 x 1 =exp { 1 xx 0 x So we get a Gaussan wth wdth σ x. Calculatons of σ y smlar, and can also show that ρ s correlaton coeffcent. x Physcs ]} ]}
13 P(x y) Px,y= { 1 x y 1 exp 1 [ xx 0 1 x yy 0 y xx yy ]} 0 0 x y Note: f you vew y as a fxed parameter, then the PDF P(x y) s a Gaussan wth wdth of: x 1 and a mean value of x 0 x y yy 0 (It makes sense that the wdth of P(x y) s always narrower than the wdth of the margnalzed PDF P(x) (ntegrated over y). If you know the actual value of y, you have addtonal nformaton and so a tghter constrant on x. Physcs
14 σ x = σ y =1 ρ=0.8 Red ellpse: contour wth argument of exponental set to equal -1/ Blue ellpse: contour contanng 68% of D probablty content. Physcs
15 Contour ellpses Px,y= { 1 x y 1 exp 1 [ xx 0 1 x The contour ellpses are defned by settng the argument of the exponent equal to a constant. The exponent equals -1/ on the red ellpse from the prevous graph. Parameters of ths ellpse are: tan = x y x y yy 0 y xx yy ]} 0 0 x y u = cos x sn y cos sn v = cos y sn x cos sn Physcs
16 Probablty content nsde a contour ellpse For a 1D Gaussan exp(-x /σ ), the ±1σ lmts occur when the argument of the exponent equals -1/. For a Gaussan there's a 68% chance of the measurement fallng wthn around the mean. But for a D Gaussan ths s not the case. Easest to see ths for the smple case of σ x =σ y =1: 1 dxdy exp[ 1 x y ] r = 0 dr exp[ 1 0 r ] =0.68 Evaluatng ths ntegral and solvng gves r 0 =.3. So 68% of probablty content s contaned wthn a radus of σ(.3). We call ths the D contour. Note that t's bgger than the 1D verson---f you pck ponts nsde the 68% contour and plot ther x coordnates, they'll span a wder range than those pcked from the 68% contour of the 1D margnalzed PDF! Physcs
17 σ x = σ y =1 ρ =0.8 Red ellpse: contour wth argument of exponental set to equal -1/ Blue ellpse: contour contanng 68% of probablty content. Physcs 509 0
18 Margnalzaton by mnmzaton Normal margnalzaton procedure: ntegrate over y. For a multdmensonal Gaussan, ths gves the same answer as fndng the extrema of the ellpse---for every x, fnd the the value of y that maxmzes the lkelhood. For example, at x=± the value of y whch maxmzes the lkelhood s just where the dashed lne touches the ellpse. The value of the lkelhood at that pont then s the value P(x) Physcs 509 1
19 Two margnalzaton procedures Normal margnalzaton procedure: ntegrate over nusance varables: Px=dyPx,y Alternate margnalzaton procedure: maxmze the lkelhood as a functon of the nusance varables, and return the result: Pxmax y Px,y (It s not necessarly the case that the resultng PDF s normalzed.) I can prove for Gaussan dstrbutons that these two margnalzaton procedures are equvalent, but cannot prove t for the general case (In fact they gve dfferent results). Bayesans always follow the frst prescrpton. Frequentsts most often use the second. Sometmes t wll be computatonally easer to apply one, sometmes the other, even for PDFs that are approxmately Gaussan. Physcs 509
20 Maxmum lkelhood estmators By far the most useful estmator s the maxmum lkelhood method. Gven your data set x 1... x N and a set of unknown parameters α, calculate the lkelhood functon N Lx 1...x N = Px =1 It's more common (and easer) to calculate -ln L nstead: N lnlx 1...x N = lnpx =1 The maxmum lkelhood estmator s that value of α whch maxmzes L as a functon of α. It can be found by mnmzng -ln L over the unknown parameters. Physcs 509 1
21 Smple example of an ML estmator Suppose that our data sample s drawn from two dfferent dstrbutons. We know the shapes of the two dstrbutons, but not what fracton of our populaton comes from dstrbuton A vs. B. We have 0 random measurements of X from the populaton. P A x= 1e ex P B x=3x P tot x=f P A x1f P B x Physcs
22 Form for the log lkelhood and the ML estmator Suppose that our data sample s drawn from two dfferent dstrbutons. We know the shapes of the two dstrbutons, but not what fracton of our populaton comes from dstrbuton A vs. B. We have 0 random measurements of X from the populaton. P tot x=f P A x1f P B x Form the negatve log lkelhood: N lnlf= lnp tot x f =1 Mnmze -ln(l) wth respect to f. Sometmes you can solve ths analytcally by settng the dervatve equal to zero. More often you have to do t numercally. Physcs
23 Graph of the log lkelhood The graph to the left shows the shape of the negatve log lkelhood functon vs. the unknown parameter f. The mnmum s f= Ths s the ML estmate. As we'll see, the 1σ error range s defned by ln(l)=0.5 above the mnmum. The data set was actually drawn from a dstrbuton wth a true value of f=0.3 Physcs
24 Errors on ML estmators In the lmt of large N, the log lkelhood becomes parabolc (by CLT). Comparng to ln(l) for a smple Gaussan: lnl=l 0 1 f f f t s natural to dentfy the 1σ range on the parameter by the ponts as whch ln(l)=½. σ range: ln(l)=½() = 3σ range: ln(l)=½(3) =4.5 Ths s done even when the lkelhood sn't parabolc (although at some perl). Physcs
25 Parabolcty of the log lkelhood In general the log lkelhood becomes more parabolc as N gets larger. The graphs at the rght show the negatve log lkelhoods for our example problem for N=0 and N=500. The red curves are parabolc fts around the mnmum. How large does N have to be before the parabolc approxmaton s good? That depends on the problem---try graphng -ln(l) vs your parameter to see how parabolc t s. Physcs
26 Asymmetrc errors from ML estmators Even when the log lkelhood s not Gaussan, t's nearly unversal to defne the 1σ range by ln(l)=½. Ths can result n asymmetrc error bars, such as: The justfcaton often gven for ths s that one could always reparameterze the estmated quantty nto one whch does have a parabolc lkelhood. Snce ML estmators are supposed to be nvarant under reparameterzatons, you could then transform back to get asymmetrc errors. Does ths procedure actually work? Physcs 509 0
27 Coverage of ML estmator errors What do we really want the ML error bars to mean? Ideally, the 1σ range would mean that the true value has 68% chance of beng wthn that range. Fracton of tme 1σ range ncludes N true value % % % % Dstrbuton of ML estmators for two N values Physcs 509 1
28 Errors on ML estmators Smulaton s the best way to estmate the true error range on an ML estmator: assume a true value for the parameter, and smulate a few hundred experments, then calculate ML estmates for each. N=0: Range from lkelhood functon: / RMS of smulaton: 0.16 N=500: Range from lkelhood functon: / RMS of smulaton: Physcs 509
29 Lkelhood functons of multple parameters Often there s more than one free parameter. To handle ths, we smply mnmze the negatve log lkelhood over all free parameters. lnlx 1...x N a 1...a m a j =0 Errors determned by (n the Gaussan approxmaton): cov 1 a,a j = lnl a a j evaluated at mnmum Physcs 509 3
30 Error contours for multple parameters We can also fnd the errors on parameters by drawng contours on ln L. 1σ range on a sngle parameter a: the smallest and largest values of a that gve ln L=½, mnmzng ln L over all other parameters. But to get jont error contours, must use dfferent values of ln L (see Num Rec Sec 15.6): m=1 m= m= % % % % Physcs 509 4
31 Maxmum Lkelhood wth Gaussan Errors Suppose we want to ft a set of ponts (x,y ) to some model y=f(x α), n order to determne the parameter(s) α. Often the measurements wll be scattered around the model wth some Gaussan error. Let's derve the ML estmator for α. N L= =1 The log lkelhood s then 1 [ exp 1 lnl= 1 N y f x =1 Maxmzng ths s equvalent to mnmzng y f x N =1 ] ln N = =1 y f x Physcs 509 3
32 The Least Squares Method Taken outsde the context of the ML method, the least squares method s the most commonly known estmator. Why? N = =1 y f x 1) Easly mplemented. ) Graphcally motvated (see ttle slde!) 3) Mathematcally straghtforward---often analytc soluton 4) Extenson of LS to correlated uncertantes straghtforward: N N = y f x y f x j V 1 j =1 j=1 Physcs 509 4
33 Least Squares Straght Lne Ft The most straghtforward example s a lnear ft: y=mx+b. = y mx b Least squares estmators for m and b are found by dfferentatng χ wth respect to m & b. d dm = y mx b d db = y mx b x =0 =0 Ths s a lnear system of smultaneous equatons wth two unknowns. Physcs 509 5
34 Solvng for m and b The most straghtforward example s a lnear ft: y=mx+b. d dm = y mx b x =0 d db = y mx b =0 x y =m x b x y =m x b 1 m= y b= y x x m x 1 1 x x y 1 (Specal case of equal σ's.) m=yxxy x x b=ymx Physcs 509 6
35 Soluton for least squares m and b There's a nce analytc soluton---rather than tryng to numercally mnmze a χ, we can just plug n values nto the formulas! Ths worked out ncely because of the very smple form of the lkelhood, due to the lnearty of the problem and the assumpton of Gaussan errors. m= y x x 1 x x y 1 (Specal case of equal errors) m=yxxy x x b= y m x 1 b=ymx Physcs 509 7
36 Errors n the Least Squares Method What about the errors and correlatons between m and b? Smplest way to derve ths s to look at the ch-squared, and remember that ths s a specal case of the ML method: lnl= 1 = 1 y mx b In the ML method, we defne the 1σ error on a parameter by the mnmum and maxmum value of that parameter satsfyng ln L=½. In LS method, ths corresponds to χ =+1 above the best-ft pont. Two sgma error range corresponds to χ =+4, 3σ s χ =+9, etc. But notce one thng about the dependence of the χ ---t s quadratc n both m and b, and generally ncludes a cross-term proportonal to mb. Concluson: Gaussan uncertantes on m and b, wth a covarance between them. Physcs 509 8
37 Formulas for Errors n the Least Squares Method We can also derve the errors by relatng the χ to the negatve log lkelhood, and usng the error formula: cov 1 a,a j = lnl a a j = lnl a a j a=a = 1 a a j a=a m = 1 1/ 1 x x = N 1 x x b = 1 1/ x x x = N cov m, b= 1 1/ x x x x xx = N (ntutve when <x>=0) x x x Physcs
38 Nonlnear least squares The dervaton of the least squares method doesn't depend on the assumpton that your fttng functon s lnear n the parameters. Nonlnear fts, such as A + B sn(ct + D), can be tackled wth the least squares technque as well. But thngs aren't nearly as nce: No closed form soluton---have to mnmze the χ numercally. Estmators are no longer guaranteed to have zero bas and mnmum varance. Contours generated by χ =+1 no longer are ellpses, and the tangents to these contours no longer gve the standard devatons. (However, we can stll nterpret them as gvng 1σ errors--- although snce the dstrbuton s non-gaussan, ths error range sn't the same thng as a standard devaton Be very careful wth mnmzaton routnes---dependng on how badly non-lnear your problem s, there may be multple solutons, local mnma, etc. Physcs
39 Goodness of ft for least squares By now you're probably wonderng why I haven't dscussed the use of χ as a goodness of ft parameter. Partly ths s because parameter estmaton and goodness of ft are logcally separate thngs---f you're CERTAIN that you've got the correct model and error estmates, then a poor χ can only be bad luck, and tells you nothng about how accurate your parameter estmates are. Carefully dstngush between: 1) Value of χ at mnmum: a measure of goodness of ft ) How quckly χ changes as a functon of the parameter: a measure of the uncertanty on the parameter. Nonetheless, a major advantage of the χ approach s that t does automatcally generate a goodness of ft parameter as a byproduct of the ft. As we'll see, the maxmum lkelhood method doesn't. How does ths work? Physcs
40 χ as a goodness of ft parameter Remember that the sum of N Gaussan varables wth zero mean and unt RMS, when squared and added, follows a χ dstrbuton wth N degrees of freedom. Compare to the least squares formula: = j y f x y j f x j V 1 j If each y s dstrbuted around the functon accordng to a Gaussan, and f(x α) s a lnear functon of the m free parameters α, and the error estmates don't depend on the free parameters, then the best-ft least squares quantty we call χ actually follows a χ dstrbuton wth N-m degrees of freedom. People usually gnore these varous caveats and assume ths works even when the parameter dependence s non-lnear and the errors aren't Gaussan. Be very careful wth ths, and check wth smulaton f you're not sure. Physcs 509 0
41 Goodness of ft: an example Does the data sample, known to have Gaussan errors, ft acceptably to a constant (flat lne)? 6 data ponts 1 free parameter = 5 d.o.f. χ = 8.85/5 d.o.f. Chance of gettng a larger χ s 1.5%---an acceptable ft by almost anyone's standard. Flat lne s a good ft. Physcs 509 1
42 Dstncton between goodness of ft and parameter estmaton Now f we ft a sloped lne to the same data, s the slope consstent wth flat. χ s obvously gong to be somewhat better. But slope s 3.5σ dfferent from zero! Chance probablty of ths s How can we smultaneously say that the same data set s acceptably ft by a flat lne and has a slope that s sgnfcantly larger than zero??? Physcs 509
43 Dstncton between goodness of ft and parameter estmaton Goodness of ft and parameter estmaton are answerng two dfferent questons. 1) Goodness of ft: s the data consstent wth havng been drawn from a specfed dstrbuton? ) Parameter estmaton: whch of the followng lmted set of hypotheses s most consstent wth the data? One way to thnk of ths s that a χ goodness of ft compares the data set to all the possble ways that random Gaussan data mght fluctuate. Parameter estmaton chooses the best of a more lmted set of hypotheses. Parameter estmaton s generally more powerful, at the expense of beng more model-dependent. Complant of the statstcally llterate: Although you say your data strongly favours soluton A, doesn't soluton B also have an acceptable χ /dof close to 1? Physcs 509 3
44 What s an error bar? Someone hands you a plot lke ths. What do the error bars ndcate? Answer: you can never be sure, unless t's specfed! Most common: vertcal error bars ndcate ±1σ uncertantes. Horzontal error bars can ndcate uncertanty on X coordnate, or can ndcate bnnng. Correlatons unknown! Physcs 509
45 Relaton of an error bar to PDF shape The error bar on a plot s most often meant to represent the ±1σ uncertanty on a data pont. Bayesans and frequentsts wll dsagree on what that means. If data s dstrbuted normally around true value, t's clear what s ntended: exp[-(x-µ) /σ ]. But for asymmetrc dstrbutons, dfferent thngs are sometmes meant... Physcs 509 3
46 An error bar s a shorthand approxmaton to a PDF! In an deal Bayesan unverse, error bars don't exst. Instead, everyone wll use the full pror PDF and the data to calculate the posteror PDF, and then report the shape of that PDF (preferably as a graph or table). An error bar s really a shorthand way to parameterze a PDF. Most often ths means pretendng the PDF s Gaussan and reportng ts mean and RMS. Many sns wth error bars come from assumng Gaussan dstrbutons when there aren't any. Physcs 509 4
47 An error bar as a confdence nterval Frequentst technques don't drectly answer the queston of what the probablty s for a parameter to have a partcular value. All you can calculate s the probablty of observng your data gven a value of the parameter.the confdence nterval constructon s a dodge to get around ths. Startng pont s the PDF for the estmator, for a fxed value of the parameter. The estmator has probablty 1 α β to fall n the whte regon. Physcs 509 5
48 The ln(l) rule It s not trval to construct proper frequentst confdence ntervals. Most often an approxmaton s used: the confdence nterval for a sngle parameter s defned as the range n whch ln(l max )-ln(l)<0.5 Ths s only an approxmaton, and does not gve exactly the rght coverage when N s small. More generally, f you have d free parameters, then the quantty ω = χ = [ln(l max )-ln(l)] approxmates a χ wth d degrees of freedom. For experts: there do exst correctons to the ln(l) rule that more accurately approxmate coverage---see Bartlett's correcton. Often MC s better way to go. Physcs 509 7
49 Error-weghted averages Suppose you have N ndependent measurements of a quantty. You average them. The proper error-weghted average s: x x= / 1/ Vx= 1 1/ If all of the uncertantes are equal, then ths reduces to the smple arthmetc mean, wth V(<x>) = V(x)/N. Physcs 509 8
50 Averagng correlated measurements II The obvous generalzaton for correlated uncertantes s to form the χ ncludng the covarance matrx: = j x x j V 1 j We fnd the best value of µ by mnmzng ths χ and can then fnd the 1σ uncertantes on µ by fndng the values of µ for whch χ = χ mn + 1. Ths s really parameter estmaton wth one varable. The best-ft value s easy enough to fnd: =,j x j V 1 j V 1 j,j Physcs
51 Averagng correlated measurements III Recognzng that the χ really just s the argument of an exponental defnng a Gaussan PDF for µ... = j x x j V 1 j we can n fact read off the coeffcent of µ, whch wll be 1/V(µ): 1 = V 1 j,j In general ths can only be computed by nvertng the matrx as far as I know. Physcs 509 1
52 The error propagaton equaton Let f(x,y) be a functon of two varables, and assume that the uncertantes on x and y are known and small. Then: f = df dx df x dy y df dx df dy x y The assumptons underlyng the error propagaton equaton are: covarances are known f s an approxmately lnear functon of x and y over the span of x±dx or y±dy. The most common mstake n the world: gnorng the thrd term. Intro courses gnore ts exstence entrely! Physcs
53 Example: nterpolatng a straght lne ft Straght lne ft y=mx+b Reported values from a standard fttng package: m = ± b = 6.81 ±.57 Estmate the value and uncertanty of y when x=45.5: y=0.658* =36.75 dy= =3.6 UGH! NONSENSE! Physcs
54 Example: straght lne ft, done correctly Here's the correct way to estmate y at x=45.5. Frst, I fnd a better ftter, whch reports the actual covarance matrx of the ft: m = b = ρ = dy= =0.16 (Snce the uncertanty on each ndvdual data pont was 0.5, and the fttng procedure effectvely averages out ther fluctuatons, then we expect that we could predct the value of y n the meat of the dstrbuton to better than 0.5.) Food for thought: f the correlatons matter so much, why don't most fttng programs report them routnely??? Physcs
55 Reducng correlatons n the straght lne ft The strong correlaton between m and b results from the long lever arm--- snce you must extrapolate lne to x=0 to determne b, a bg error on m makes a bg error on b. You can avod strong correlatons by usng more sensble parameterzatons: for example, ft data to y=b'+m(x-45.5): b' = ± 0.16 m = ±.085 ρ = 0.43 dy at x=45.5 = 0.16 Physcs 509 0
THE METHOD OF LEAST SQUARES THE METHOD OF LEAST SQUARES
The goal: to measure (determne) an unknown quantty x (the value of a RV X) Realsaton: n results: y 1, y 2,..., y j,..., y n, (the measured values of Y 1, Y 2,..., Y j,..., Y n ) every result s encumbered
More informationCausal, Explanatory Forecasting. Analysis. Regression Analysis. Simple Linear Regression. Which is Independent? Forecasting
Causal, Explanatory Forecastng Assumes cause-and-effect relatonshp between system nputs and ts output Forecastng wth Regresson Analyss Rchard S. Barr Inputs System Cause + Effect Relatonshp The job of
More information8.5 UNITARY AND HERMITIAN MATRICES. The conjugate transpose of a complex matrix A, denoted by A*, is given by
6 CHAPTER 8 COMPLEX VECTOR SPACES 5. Fnd the kernel of the lnear transformaton gven n Exercse 5. In Exercses 55 and 56, fnd the mage of v, for the ndcated composton, where and are gven by the followng
More informationSIMPLE LINEAR CORRELATION
SIMPLE LINEAR CORRELATION Smple lnear correlaton s a measure of the degree to whch two varables vary together, or a measure of the ntensty of the assocaton between two varables. Correlaton often s abused.
More informationbenefit is 2, paid if the policyholder dies within the year, and probability of death within the year is ).
REVIEW OF RISK MANAGEMENT CONCEPTS LOSS DISTRIBUTIONS AND INSURANCE Loss and nsurance: When someone s subject to the rsk of ncurrng a fnancal loss, the loss s generally modeled usng a random varable or
More informationWhat is Candidate Sampling
What s Canddate Samplng Say we have a multclass or mult label problem where each tranng example ( x, T ) conssts of a context x a small (mult)set of target classes T out of a large unverse L of possble
More informationQuantization Effects in Digital Filters
Quantzaton Effects n Dgtal Flters Dstrbuton of Truncaton Errors In two's complement representaton an exact number would have nfntely many bts (n general). When we lmt the number of bts to some fnte value
More information1. Measuring association using correlation and regression
How to measure assocaton I: Correlaton. 1. Measurng assocaton usng correlaton and regresson We often would lke to know how one varable, such as a mother's weght, s related to another varable, such as a
More informationSPEE Recommended Evaluation Practice #6 Definition of Decline Curve Parameters Background:
SPEE Recommended Evaluaton Practce #6 efnton of eclne Curve Parameters Background: The producton hstores of ol and gas wells can be analyzed to estmate reserves and future ol and gas producton rates and
More informationLatent Class Regression. Statistics for Psychosocial Research II: Structural Models December 4 and 6, 2006
Latent Class Regresson Statstcs for Psychosocal Research II: Structural Models December 4 and 6, 2006 Latent Class Regresson (LCR) What s t and when do we use t? Recall the standard latent class model
More informationHow To Calculate The Accountng Perod Of Nequalty
Inequalty and The Accountng Perod Quentn Wodon and Shlomo Ytzha World Ban and Hebrew Unversty September Abstract Income nequalty typcally declnes wth the length of tme taen nto account for measurement.
More informationPSYCHOLOGICAL RESEARCH (PYC 304-C) Lecture 12
14 The Ch-squared dstrbuton PSYCHOLOGICAL RESEARCH (PYC 304-C) Lecture 1 If a normal varable X, havng mean µ and varance σ, s standardsed, the new varable Z has a mean 0 and varance 1. When ths standardsed
More informationCHAPTER 14 MORE ABOUT REGRESSION
CHAPTER 14 MORE ABOUT REGRESSION We learned n Chapter 5 that often a straght lne descrbes the pattern of a relatonshp between two quanttatve varables. For nstance, n Example 5.1 we explored the relatonshp
More informationCHAPTER 5 RELATIONSHIPS BETWEEN QUANTITATIVE VARIABLES
CHAPTER 5 RELATIONSHIPS BETWEEN QUANTITATIVE VARIABLES In ths chapter, we wll learn how to descrbe the relatonshp between two quanttatve varables. Remember (from Chapter 2) that the terms quanttatve varable
More information+ + + - - This circuit than can be reduced to a planar circuit
MeshCurrent Method The meshcurrent s analog of the nodeoltage method. We sole for a new set of arables, mesh currents, that automatcally satsfy KCLs. As such, meshcurrent method reduces crcut soluton to
More informationNMT EE 589 & UNM ME 482/582 ROBOT ENGINEERING. Dr. Stephen Bruder NMT EE 589 & UNM ME 482/582
NMT EE 589 & UNM ME 482/582 ROBOT ENGINEERING Dr. Stephen Bruder NMT EE 589 & UNM ME 482/582 7. Root Dynamcs 7.2 Intro to Root Dynamcs We now look at the forces requred to cause moton of the root.e. dynamcs!!
More informationCS 2750 Machine Learning. Lecture 3. Density estimation. CS 2750 Machine Learning. Announcements
Lecture 3 Densty estmaton Mlos Hauskrecht mlos@cs.ptt.edu 5329 Sennott Square Next lecture: Matlab tutoral Announcements Rules for attendng the class: Regstered for credt Regstered for audt (only f there
More informationCHOLESTEROL REFERENCE METHOD LABORATORY NETWORK. Sample Stability Protocol
CHOLESTEROL REFERENCE METHOD LABORATORY NETWORK Sample Stablty Protocol Background The Cholesterol Reference Method Laboratory Network (CRMLN) developed certfcaton protocols for total cholesterol, HDL
More informationThe OC Curve of Attribute Acceptance Plans
The OC Curve of Attrbute Acceptance Plans The Operatng Characterstc (OC) curve descrbes the probablty of acceptng a lot as a functon of the lot s qualty. Fgure 1 shows a typcal OC Curve. 10 8 6 4 1 3 4
More informationModule 2 LOSSLESS IMAGE COMPRESSION SYSTEMS. Version 2 ECE IIT, Kharagpur
Module LOSSLESS IMAGE COMPRESSION SYSTEMS Lesson 3 Lossless Compresson: Huffman Codng Instructonal Objectves At the end of ths lesson, the students should be able to:. Defne and measure source entropy..
More informationNPAR TESTS. One-Sample Chi-Square Test. Cell Specification. Observed Frequencies 1O i 6. Expected Frequencies 1EXP i 6
PAR TESTS If a WEIGHT varable s specfed, t s used to replcate a case as many tmes as ndcated by the weght value rounded to the nearest nteger. If the workspace requrements are exceeded and samplng has
More informationSupport Vector Machines
Support Vector Machnes Max Wellng Department of Computer Scence Unversty of Toronto 10 Kng s College Road Toronto, M5S 3G5 Canada wellng@cs.toronto.edu Abstract Ths s a note to explan support vector machnes.
More informationCalculation of Sampling Weights
Perre Foy Statstcs Canada 4 Calculaton of Samplng Weghts 4.1 OVERVIEW The basc sample desgn used n TIMSS Populatons 1 and 2 was a two-stage stratfed cluster desgn. 1 The frst stage conssted of a sample
More informationPortfolio Loss Distribution
Portfolo Loss Dstrbuton Rsky assets n loan ortfolo hghly llqud assets hold-to-maturty n the bank s balance sheet Outstandngs The orton of the bank asset that has already been extended to borrowers. Commtment
More informationLogistic Regression. Lecture 4: More classifiers and classes. Logistic regression. Adaboost. Optimization. Multiple class classification
Lecture 4: More classfers and classes C4B Machne Learnng Hlary 20 A. Zsserman Logstc regresson Loss functons revsted Adaboost Loss functons revsted Optmzaton Multple class classfcaton Logstc Regresson
More informationRecurrence. 1 Definitions and main statements
Recurrence 1 Defntons and man statements Let X n, n = 0, 1, 2,... be a MC wth the state space S = (1, 2,...), transton probabltes p j = P {X n+1 = j X n = }, and the transton matrx P = (p j ),j S def.
More informationL10: Linear discriminants analysis
L0: Lnear dscrmnants analyss Lnear dscrmnant analyss, two classes Lnear dscrmnant analyss, C classes LDA vs. PCA Lmtatons of LDA Varants of LDA Other dmensonalty reducton methods CSCE 666 Pattern Analyss
More informationSTATISTICAL DATA ANALYSIS IN EXCEL
Mcroarray Center STATISTICAL DATA ANALYSIS IN EXCEL Lecture 6 Some Advanced Topcs Dr. Petr Nazarov 14-01-013 petr.nazarov@crp-sante.lu Statstcal data analyss n Ecel. 6. Some advanced topcs Correcton for
More informationCalibration and Linear Regression Analysis: A Self-Guided Tutorial
Calbraton and Lnear Regresson Analyss: A Self-Guded Tutoral Part The Calbraton Curve, Correlaton Coeffcent and Confdence Lmts CHM314 Instrumental Analyss Department of Chemstry, Unversty of Toronto Dr.
More informationTHE DISTRIBUTION OF LOAN PORTFOLIO VALUE * Oldrich Alfons Vasicek
HE DISRIBUION OF LOAN PORFOLIO VALUE * Oldrch Alfons Vascek he amount of captal necessary to support a portfolo of debt securtes depends on the probablty dstrbuton of the portfolo loss. Consder a portfolo
More informationThe Mathematical Derivation of Least Squares
Pscholog 885 Prof. Federco The Mathematcal Dervaton of Least Squares Back when the powers that e forced ou to learn matr algera and calculus, I et ou all asked ourself the age-old queston: When the hell
More informationEconomic Interpretation of Regression. Theory and Applications
Economc Interpretaton of Regresson Theor and Applcatons Classcal and Baesan Econometrc Methods Applcaton of mathematcal statstcs to economc data for emprcal support Economc theor postulates a qualtatve
More informationBERNSTEIN POLYNOMIALS
On-Lne Geometrc Modelng Notes BERNSTEIN POLYNOMIALS Kenneth I. Joy Vsualzaton and Graphcs Research Group Department of Computer Scence Unversty of Calforna, Davs Overvew Polynomals are ncredbly useful
More information1 Example 1: Axis-aligned rectangles
COS 511: Theoretcal Machne Learnng Lecturer: Rob Schapre Lecture # 6 Scrbe: Aaron Schld February 21, 2013 Last class, we dscussed an analogue for Occam s Razor for nfnte hypothess spaces that, n conjuncton
More informationHÜCKEL MOLECULAR ORBITAL THEORY
1 HÜCKEL MOLECULAR ORBITAL THEORY In general, the vast maorty polyatomc molecules can be thought of as consstng of a collecton of two electron bonds between pars of atoms. So the qualtatve pcture of σ
More informationAn Alternative Way to Measure Private Equity Performance
An Alternatve Way to Measure Prvate Equty Performance Peter Todd Parlux Investment Technology LLC Summary Internal Rate of Return (IRR) s probably the most common way to measure the performance of prvate
More informationn + d + q = 24 and.05n +.1d +.25q = 2 { n + d + q = 24 (3) n + 2d + 5q = 40 (2)
MATH 16T Exam 1 : Part I (In-Class) Solutons 1. (0 pts) A pggy bank contans 4 cons, all of whch are nckels (5 ), dmes (10 ) or quarters (5 ). The pggy bank also contans a con of each denomnaton. The total
More informationLogistic Regression. Steve Kroon
Logstc Regresson Steve Kroon Course notes sectons: 24.3-24.4 Dsclamer: these notes do not explctly ndcate whether values are vectors or scalars, but expects the reader to dscern ths from the context. Scenaro
More informationMean Molecular Weight
Mean Molecular Weght The thermodynamc relatons between P, ρ, and T, as well as the calculaton of stellar opacty requres knowledge of the system s mean molecular weght defned as the mass per unt mole of
More informationGRAVITY DATA VALIDATION AND OUTLIER DETECTION USING L 1 -NORM
GRAVITY DATA VALIDATION AND OUTLIER DETECTION USING L 1 -NORM BARRIOT Jean-Perre, SARRAILH Mchel BGI/CNES 18.av.E.Beln 31401 TOULOUSE Cedex 4 (France) Emal: jean-perre.barrot@cnes.fr 1/Introducton The
More information) of the Cell class is created containing information about events associated with the cell. Events are added to the Cell instance
Calbraton Method Instances of the Cell class (one nstance for each FMS cell) contan ADC raw data and methods assocated wth each partcular FMS cell. The calbraton method ncludes event selecton (Class Cell
More informationLinear Circuits Analysis. Superposition, Thevenin /Norton Equivalent circuits
Lnear Crcuts Analyss. Superposton, Theenn /Norton Equalent crcuts So far we hae explored tmendependent (resste) elements that are also lnear. A tmendependent elements s one for whch we can plot an / cure.
More informationThe Greedy Method. Introduction. 0/1 Knapsack Problem
The Greedy Method Introducton We have completed data structures. We now are gong to look at algorthm desgn methods. Often we are lookng at optmzaton problems whose performance s exponental. For an optmzaton
More informationv a 1 b 1 i, a 2 b 2 i,..., a n b n i.
SECTION 8.4 COMPLEX VECTOR SPACES AND INNER PRODUCTS 455 8.4 COMPLEX VECTOR SPACES AND INNER PRODUCTS All the vector spaces we have studed thus far n the text are real vector spaces snce the scalars are
More informationLeast Squares Fitting of Data
Least Squares Fttng of Data Davd Eberly Geoetrc Tools, LLC http://www.geoetrctools.co/ Copyrght c 1998-2016. All Rghts Reserved. Created: July 15, 1999 Last Modfed: January 5, 2015 Contents 1 Lnear Fttng
More informationwhere the coordinates are related to those in the old frame as follows.
Chapter 2 - Cartesan Vectors and Tensors: Ther Algebra Defnton of a vector Examples of vectors Scalar multplcaton Addton of vectors coplanar vectors Unt vectors A bass of non-coplanar vectors Scalar product
More informationSection 5.4 Annuities, Present Value, and Amortization
Secton 5.4 Annutes, Present Value, and Amortzaton Present Value In Secton 5.2, we saw that the present value of A dollars at nterest rate per perod for n perods s the amount that must be deposted today
More informationA Probabilistic Theory of Coherence
A Probablstc Theory of Coherence BRANDEN FITELSON. The Coherence Measure C Let E be a set of n propostons E,..., E n. We seek a probablstc measure C(E) of the degree of coherence of E. Intutvely, we want
More informationTexas Instruments 30X IIS Calculator
Texas Instruments 30X IIS Calculator Keystrokes for the TI-30X IIS are shown for a few topcs n whch keystrokes are unque. Start by readng the Quk Start secton. Then, before begnnng a specfc unt of the
More informationLecture 2: Single Layer Perceptrons Kevin Swingler
Lecture 2: Sngle Layer Perceptrons Kevn Sngler kms@cs.str.ac.uk Recap: McCulloch-Ptts Neuron Ths vastly smplfed model of real neurons s also knon as a Threshold Logc Unt: W 2 A Y 3 n W n. A set of synapses
More informationFeature selection for intrusion detection. Slobodan Petrović NISlab, Gjøvik University College
Feature selecton for ntruson detecton Slobodan Petrovć NISlab, Gjøvk Unversty College Contents The feature selecton problem Intruson detecton Traffc features relevant for IDS The CFS measure The mrmr measure
More informationLuby s Alg. for Maximal Independent Sets using Pairwise Independence
Lecture Notes for Randomzed Algorthms Luby s Alg. for Maxmal Independent Sets usng Parwse Independence Last Updated by Erc Vgoda on February, 006 8. Maxmal Independent Sets For a graph G = (V, E), an ndependent
More informationExhaustive Regression. An Exploration of Regression-Based Data Mining Techniques Using Super Computation
Exhaustve Regresson An Exploraton of Regresson-Based Data Mnng Technques Usng Super Computaton Antony Daves, Ph.D. Assocate Professor of Economcs Duquesne Unversty Pttsburgh, PA 58 Research Fellow The
More informationCan Auto Liability Insurance Purchases Signal Risk Attitude?
Internatonal Journal of Busness and Economcs, 2011, Vol. 10, No. 2, 159-164 Can Auto Lablty Insurance Purchases Sgnal Rsk Atttude? Chu-Shu L Department of Internatonal Busness, Asa Unversty, Tawan Sheng-Chang
More informationHow Sets of Coherent Probabilities May Serve as Models for Degrees of Incoherence
1 st Internatonal Symposum on Imprecse Probabltes and Ther Applcatons, Ghent, Belgum, 29 June 2 July 1999 How Sets of Coherent Probabltes May Serve as Models for Degrees of Incoherence Mar J. Schervsh
More informationRegression Models for a Binary Response Using EXCEL and JMP
SEMATECH 997 Statstcal Methods Symposum Austn Regresson Models for a Bnary Response Usng EXCEL and JMP Davd C. Trndade, Ph.D. STAT-TECH Consultng and Tranng n Appled Statstcs San Jose, CA Topcs Practcal
More informationSection 2 Introduction to Statistical Mechanics
Secton 2 Introducton to Statstcal Mechancs 2.1 Introducng entropy 2.1.1 Boltzmann s formula A very mportant thermodynamc concept s that of entropy S. Entropy s a functon of state, lke the nternal energy.
More informationHedging Interest-Rate Risk with Duration
FIXED-INCOME SECURITIES Chapter 5 Hedgng Interest-Rate Rsk wth Duraton Outlne Prcng and Hedgng Prcng certan cash-flows Interest rate rsk Hedgng prncples Duraton-Based Hedgng Technques Defnton of duraton
More informationAnswer: A). There is a flatter IS curve in the high MPC economy. Original LM LM after increase in M. IS curve for low MPC economy
4.02 Quz Solutons Fall 2004 Multple-Choce Questons (30/00 ponts) Please, crcle the correct answer for each of the followng 0 multple-choce questons. For each queston, only one of the answers s correct.
More informationInter-Ing 2007. INTERDISCIPLINARITY IN ENGINEERING SCIENTIFIC INTERNATIONAL CONFERENCE, TG. MUREŞ ROMÂNIA, 15-16 November 2007.
Inter-Ing 2007 INTERDISCIPLINARITY IN ENGINEERING SCIENTIFIC INTERNATIONAL CONFERENCE, TG. MUREŞ ROMÂNIA, 15-16 November 2007. UNCERTAINTY REGION SIMULATION FOR A SERIAL ROBOT STRUCTURE MARIUS SEBASTIAN
More informationCharacterization of Assembly. Variation Analysis Methods. A Thesis. Presented to the. Department of Mechanical Engineering. Brigham Young University
Characterzaton of Assembly Varaton Analyss Methods A Thess Presented to the Department of Mechancal Engneerng Brgham Young Unversty In Partal Fulfllment of the Requrements for the Degree Master of Scence
More informationAnalysis of Premium Liabilities for Australian Lines of Business
Summary of Analyss of Premum Labltes for Australan Lnes of Busness Emly Tao Honours Research Paper, The Unversty of Melbourne Emly Tao Acknowledgements I am grateful to the Australan Prudental Regulaton
More informationA machine vision approach for detecting and inspecting circular parts
A machne vson approach for detectng and nspectng crcular parts Du-Mng Tsa Machne Vson Lab. Department of Industral Engneerng and Management Yuan-Ze Unversty, Chung-L, Tawan, R.O.C. E-mal: edmtsa@saturn.yzu.edu.tw
More informationEfficient Project Portfolio as a tool for Enterprise Risk Management
Effcent Proect Portfolo as a tool for Enterprse Rsk Management Valentn O. Nkonov Ural State Techncal Unversty Growth Traectory Consultng Company January 5, 27 Effcent Proect Portfolo as a tool for Enterprse
More informationIntroduction to Statistical Physics (2SP)
Introducton to Statstcal Physcs (2SP) Rchard Sear March 5, 20 Contents What s the entropy (aka the uncertanty)? 2. One macroscopc state s the result of many many mcroscopc states.......... 2.2 States wth
More informationTraffic-light a stress test for life insurance provisions
MEMORANDUM Date 006-09-7 Authors Bengt von Bahr, Göran Ronge Traffc-lght a stress test for lfe nsurance provsons Fnansnspetonen P.O. Box 6750 SE-113 85 Stocholm [Sveavägen 167] Tel +46 8 787 80 00 Fax
More informationIS-LM Model 1 C' dy = di
- odel Solow Assumptons - demand rrelevant n long run; assumes economy s operatng at potental GDP; concerned wth growth - Assumptons - supply s rrelevant n short run; assumes economy s operatng below potental
More informationEnergies of Network Nastsemble
Supplementary materal: Assessng the relevance of node features for network structure Gnestra Bancon, 1 Paolo Pn,, 3 and Matteo Marsl 1 1 The Abdus Salam Internatonal Center for Theoretcal Physcs, Strada
More informationFisher Markets and Convex Programs
Fsher Markets and Convex Programs Nkhl R. Devanur 1 Introducton Convex programmng dualty s usually stated n ts most general form, wth convex objectve functons and convex constrants. (The book by Boyd and
More informationInstitute of Informatics, Faculty of Business and Management, Brno University of Technology,Czech Republic
Lagrange Multplers as Quanttatve Indcators n Economcs Ivan Mezník Insttute of Informatcs, Faculty of Busness and Management, Brno Unversty of TechnologCzech Republc Abstract The quanttatve role of Lagrange
More informationExtending Probabilistic Dynamic Epistemic Logic
Extendng Probablstc Dynamc Epstemc Logc Joshua Sack May 29, 2008 Probablty Space Defnton A probablty space s a tuple (S, A, µ), where 1 S s a set called the sample space. 2 A P(S) s a σ-algebra: a set
More informationChapter 7: Answers to Questions and Problems
19. Based on the nformaton contaned n Table 7-3 of the text, the food and apparel ndustres are most compettve and therefore probably represent the best match for the expertse of these managers. Chapter
More informationSeries Solutions of ODEs 2 the Frobenius method. The basic idea of the Frobenius method is to look for solutions of the form 3
Royal Holloway Unversty of London Department of Physs Seres Solutons of ODEs the Frobenus method Introduton to the Methodology The smple seres expanson method works for dfferental equatons whose solutons
More informationANALYZING THE RELATIONSHIPS BETWEEN QUALITY, TIME, AND COST IN PROJECT MANAGEMENT DECISION MAKING
ANALYZING THE RELATIONSHIPS BETWEEN QUALITY, TIME, AND COST IN PROJECT MANAGEMENT DECISION MAKING Matthew J. Lberatore, Department of Management and Operatons, Vllanova Unversty, Vllanova, PA 19085, 610-519-4390,
More informationLecture 3: Force of Interest, Real Interest Rate, Annuity
Lecture 3: Force of Interest, Real Interest Rate, Annuty Goals: Study contnuous compoundng and force of nterest Dscuss real nterest rate Learn annuty-mmedate, and ts present value Study annuty-due, and
More informationVasicek s Model of Distribution of Losses in a Large, Homogeneous Portfolio
Vascek s Model of Dstrbuton of Losses n a Large, Homogeneous Portfolo Stephen M Schaefer London Busness School Credt Rsk Electve Summer 2012 Vascek s Model Important method for calculatng dstrbuton of
More informationJoe Pimbley, unpublished, 2005. Yield Curve Calculations
Joe Pmbley, unpublshed, 005. Yeld Curve Calculatons Background: Everythng s dscount factors Yeld curve calculatons nclude valuaton of forward rate agreements (FRAs), swaps, nterest rate optons, and forward
More informationProperties of real networks: degree distribution
Propertes of real networks: degree dstrbuton Nodes wth small degrees are most frequent. The fracton of hghly connected nodes decreases, but s not zero. Look closer: use a logarthmc plot. 10 0 10-1 10 0
More information1 De nitions and Censoring
De ntons and Censorng. Survval Analyss We begn by consderng smple analyses but we wll lead up to and take a look at regresson on explanatory factors., as n lnear regresson part A. The mportant d erence
More informationStatistical Methods to Develop Rating Models
Statstcal Methods to Develop Ratng Models [Evelyn Hayden and Danel Porath, Österrechsche Natonalbank and Unversty of Appled Scences at Manz] Source: The Basel II Rsk Parameters Estmaton, Valdaton, and
More informationWe are now ready to answer the question: What are the possible cardinalities for finite fields?
Chapter 3 Fnte felds We have seen, n the prevous chapters, some examples of fnte felds. For example, the resdue class rng Z/pZ (when p s a prme) forms a feld wth p elements whch may be dentfed wth the
More information1.2 DISTRIBUTIONS FOR CATEGORICAL DATA
DISTRIBUTIONS FOR CATEGORICAL DATA 5 present models for a categorcal response wth matched pars; these apply, for nstance, wth a categorcal response measured for the same subjects at two tmes. Chapter 11
More informationEvaluating credit risk models: A critique and a new proposal
Evaluatng credt rsk models: A crtque and a new proposal Hergen Frerchs* Gunter Löffler Unversty of Frankfurt (Man) February 14, 2001 Abstract Evaluatng the qualty of credt portfolo rsk models s an mportant
More informationCredit Limit Optimization (CLO) for Credit Cards
Credt Lmt Optmzaton (CLO) for Credt Cards Vay S. Desa CSCC IX, Ednburgh September 8, 2005 Copyrght 2003, SAS Insttute Inc. All rghts reserved. SAS Propretary Agenda Background Tradtonal approaches to credt
More informationtotal A A reag total A A r eag
hapter 5 Standardzng nalytcal Methods hapter Overvew 5 nalytcal Standards 5B albratng the Sgnal (S total ) 5 Determnng the Senstvty (k ) 5D Lnear Regresson and albraton urves 5E ompensatng for the Reagent
More informationRate-Based Daily Arrival Process Models with Application to Call Centers
Submtted to Operatons Research manuscrpt (Please, provde the manuscrpt number!) Authors are encouraged to submt new papers to INFORMS journals by means of a style fle template, whch ncludes the journal
More informationMultiple stage amplifiers
Multple stage amplfers Ams: Examne a few common 2-transstor amplfers: -- Dfferental amplfers -- Cascode amplfers -- Darlngton pars -- current mrrors Introduce formal methods for exactly analysng multple
More informationBrigid Mullany, Ph.D University of North Carolina, Charlotte
Evaluaton And Comparson Of The Dfferent Standards Used To Defne The Postonal Accuracy And Repeatablty Of Numercally Controlled Machnng Center Axes Brgd Mullany, Ph.D Unversty of North Carolna, Charlotte
More informationPrediction of Disability Frequencies in Life Insurance
Predcton of Dsablty Frequences n Lfe Insurance Bernhard Köng Fran Weber Maro V. Wüthrch October 28, 2011 Abstract For the predcton of dsablty frequences, not only the observed, but also the ncurred but
More informationECONOMICS OF PLANT ENERGY SAVINGS PROJECTS IN A CHANGING MARKET Douglas C White Emerson Process Management
ECONOMICS OF PLANT ENERGY SAVINGS PROJECTS IN A CHANGING MARKET Douglas C Whte Emerson Process Management Abstract Energy prces have exhbted sgnfcant volatlty n recent years. For example, natural gas prces
More informationHow To Find The Dsablty Frequency Of A Clam
1 Predcton of Dsablty Frequences n Lfe Insurance Bernhard Köng 1, Fran Weber 1, Maro V. Wüthrch 2 Abstract: For the predcton of dsablty frequences, not only the observed, but also the ncurred but not yet
More information21 Vectors: The Cross Product & Torque
21 Vectors: The Cross Product & Torque Do not use our left hand when applng ether the rght-hand rule for the cross product of two vectors dscussed n ths chapter or the rght-hand rule for somethng curl
More informationNONLINEAR OPTIMIZATION FOR PROJECT SCHEDULING AND RESOURCE ALLOCATION UNDER UNCERTAINTY
NONLINEAR OPTIMIZATION FOR PROJECT SCHEDULING AND RESOURCE ALLOCATION UNDER UNCERTAINTY A Dssertaton Presented to the Faculty of the Graduate School of Cornell Unversty In Partal Fulfllment of the Requrements
More informationProject Networks With Mixed-Time Constraints
Project Networs Wth Mxed-Tme Constrants L Caccetta and B Wattananon Western Australan Centre of Excellence n Industral Optmsaton (WACEIO) Curtn Unversty of Technology GPO Box U1987 Perth Western Australa
More informationQUESTIONS, How can quantum computers do the amazing things that they are able to do, such. cryptography quantum computers
2O cryptography quantum computers cryptography quantum computers QUESTIONS, Quantum Computers, and Cryptography A mathematcal metaphor for the power of quantum algorthms Mark Ettnger How can quantum computers
More informationHow To Understand The Results Of The German Meris Cloud And Water Vapour Product
Ttel: Project: Doc. No.: MERIS level 3 cloud and water vapour products MAPP MAPP-ATBD-ClWVL3 Issue: 1 Revson: 0 Date: 9.12.1998 Functon Name Organsaton Sgnature Date Author: Bennartz FUB Preusker FUB Schüller
More informationRichard W. Andrews and William C. Birdsall, University of Michigan Richard W. Andrews, Michigan Business School, Ann Arbor, MI 48109-1234.
SIMULTANEOUS CONFIDENCE INTERVALS: A COMPARISON UNDER COMPLEX SAMPLING Rchard W. Andrews and Wllam C. Brdsall, Unversty of Mchgan Rchard W. Andrews, Mchgan Busness School, Ann Arbor, MI 48109-1234 EY WORDS:
More informationProblem Set 3. a) We are asked how people will react, if the interest rate i on bonds is negative.
Queston roblem Set 3 a) We are asked how people wll react, f the nterest rate on bonds s negatve. When
More information1. Fundamentals of probability theory 2. Emergence of communication traffic 3. Stochastic & Markovian Processes (SP & MP)
6.3 / -- Communcaton Networks II (Görg) SS20 -- www.comnets.un-bremen.de Communcaton Networks II Contents. Fundamentals of probablty theory 2. Emergence of communcaton traffc 3. Stochastc & Markovan Processes
More informationSoftware Alignment for Tracking Detectors
Software Algnment for Trackng Detectors V. Blobel Insttut für Expermentalphysk, Unverstät Hamburg, Germany Abstract Trackng detectors n hgh energy physcs experments requre an accurate determnaton of a
More information