OMG! Excessive Texting Tied to Risky Teen Behaviors

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1 BUSIESS WEEK: EXECUTIVE EALT ovember 09, 2010 OMG! Excessive Textig Tied to Risky Tee Behaviors Kids who sed more tha 120 a day more likely to try drugs, alcohol ad sex, researchers fid TUESDAY, ov. 9 (ealthday ews) -- Excessive textig ad social etworkig may icrease tees' risk for dagerous health behaviors, icludig smokig, drikig ad sexual activity, a ew study suggests. Researchers looked at hyper-textig (sedig more tha 120 messages per school day) ad hyper-etworkig (spedig more tha three hours a school day o social etworkig sites) amog high school studets i a urba couty i the U.S. Midwest. May of the 19.8 percet of tees who reported hyper-textig were female, miority, from lower socioecoomic status ad had o father at home, accordig to the researchers at Case Wester Reserve School of Medicie i Clevelad. yper-texters were: 40 percet more likely to have tried smokig; two times more likely to have tried alcohol; 43 percet more likely to bige-drik; 41 percet more likely to have used illicit drugs; 55 percet more likely to have bee i a physical fight; early 3.5 times more likely to have had sex; ad 90 percet more likely to have had four or more sexual parters. The 11.5 percet of studets who were hyper-etworkers were: 62 percet more likely to have smoked cigarettes; 79 percet more likely to have tried alcohol; 69 percet more likely to be bige drikers; 84 percet more likely to have used illicit drugs; 94 percet more likely to have bee i a physical fight; 69 percet more likely to have had sex; ad 60 percet more likely to have had four or more sexual parters. yper-etworkig was also associated with icreased likelihood of stress, depressio, suicide, poor sleep, poor academics, televisio watchig ad paretal permissiveess. The study was to be preseted Tuesday at the America Public ealth Associatio aual meetig i Dever. "The startlig results of this study suggest that whe left uchecked, textig ad other widely popular methods of stayig coected ca have dagerous health effects o teeagers," lead researcher Dr. Scott Frak, director of the School of Medicie's Master of Public ealth Program, said i a uiversity ews release. "This should be a wake-up call for parets to ot oly help their childre stay safe by ot textig ad drivig, but by discouragig excessive use of the cell phoe or social web sites i geeral," he added. SOURCE: Case Wester Reserve School of Medicie, ews release, ov. 9, 2010 Copyright 2010 ealthday. All rights reserved. OMG! Page 1

2 Uits: Teeagers (from urba areas i the Midwest we cofie coclusios to such teeagers). Explaatory Variable: Whether or ot a perso is a hypertexter. Categorical This is a observatioal study. 2 categories / levels Respose Variable: Whether or ot a perso has tried illicit drugs. Categorical 4 rows of the data table, showig all level combiatios Summary of the raw data two categories / levels Teeager Textig Activity Use of Illicit Drugs Illicit Drug Use Wada yper Tried Textig Activity Tried ot Tried Total Xavier yper ot tried yper Yolada ohyper Tried ohyper Zach ohyper ot tried Totals ere s a clear, simple, ad effective report of the survey results. % of teeagers who have tried illicit drugs Amog hypertexters: 44.0% ( 116) Amog ohypertexters: 31.5% ( 143) 95% cofidece itervals for the proportios of all teeagers who have tried illicit drugs: Amog hypertexters: < p < Amog ohypertexters: < p < Goal: A 95% cofidece iterval for the differece betwee populatio proportios, p p. With a categorical (two levels) respose variable ad categorical (two levels) explaatory variable we hope to use the two sample Z procedures for the differece betwee proportios. Requiremet: Radom samplig; Idepedet samples; Populatio size at least 20 times the sample size; All couts i the summary of raw data at least 5. Poit estimate of differece: Error margi for differece: 95% cofidece iterval: < p p < Iterpretate the iterval: I am 95% cofidet that For a test ( 0.05) of 0 : p p 1 : p > p what s the decisio? OMG! Page 2

3 ere are the results of the hypertextig/illicit drugs iformatio, ow split by the how may parets variable. For teeagers with two parets 2 PARETS Illicit Drugs For the 2-paret teeagers, test Textig Tried ot Total ypertexters ohypertexters Total Estimated differece Test statistic: Z p p P-value Coclusio: At the 5% level 0 : p p 1 : p p Pooled proportio p For teeagers with oe paret 1 PARET Illicit Drugs For the 1-paret teeagers, test Textig Tried ot Total ypertexters ohypertexters Total Pooled proportio p Test statistic: Z p p P-value Coclusio: At the 5% level 0 : p p 1 : p p Estimated differece OMG! Page 3

4 For all teeagers ere are the results aggregated over the how may parets variable (as o page 1 we earlier obtaied the cofidece iterval). This assesses the hypertextig explaatory variable. ALL Illicit Drugs 0 : p p 1 : p p Textig Tried ot Total Test statistic: Z 2.07 ypertexters P-value ohypertexters % cofidece iterval: Total < p p < Coclusio: At the 5% level Reread Dr. Frak s statemet. What do you thik? ere are the results aggregated over the whether or ot a hypertexter variable, ad istead compared o umber of parets (assessig the umber of parets explaatory variable). 1 The subscriptig o the p s is chaged to reflect this. otice that the totals match those from above ad o the other side. ALL Illicit Drugs 0 : p1 p2 1 : p1 p2 # of parets Tried ot Total ˆp ˆp Total % cofidece iterval: E p ˆ2 Z 7.98 P-value 99% CI: < p1 p2 < Coclusio: 1 This aalysis is appropriate, because we ca see from the split o the reverse side that there is virtually o effect of hypertextig o the likelihood of tryig illicit drug use. OMG! Page 4

5 Solutios Page 2 The poit estimate is The error margi is This ca also be computed from scratch (without kowig the two idividual error margis): The cofidece iterval bouds are ± which gives < p p < I am 95% cofidet that the proportio of all teeage hypertexters who have tried illicit drugs is betwee ad higher tha the proportio of all ohypertexters who have tried illicit drugs. Sice the cofidece iterval implies that p is higher tha p, the decisio is to reject the ull hypothesis. Page 3 Teeagers with two parets The two estimated proportios are p ˆ ad p ˆ The estimate differece is (ot very big at all.) The pooled proportio is p The test statistic is Z This is a right tailed test; the P-value is the area to the right of 0.29: P-value There is virtually o evidece i favor of the alterative hypothesis. At the 5% level there is to sufficiet evidece i the data to coclude that the proportio of all hypertexters who have tried illicit drugs is higher tha the proportio of all ohypertexters who have tried illicit drugs. Teeagers with oe paret The two estimated proportios are ad The estimated differece is that s about 1% ad i the wrog directio from what is suggested i the alterative hypothesis. There is O evidece agaist the ull here. The pooled proportio is The deomiator of the test statistic (the stadard error SE ) is The test statistic is / The P-value is At the 5% level there is isufficiet evidece i the data to coclude that the proportio of all hypertexters who have tried illicit drugs is higher tha the proportio of all ohypertexters who have tried illicit drugs. I fact: There is O evidece of this. The observed differece is opposite i sig to this. OMG! Page 5

6 Page 4 Aggregated over the how may parets variable, assessig the effects of hypertextig At the 5% level there is sufficiet evidece i the sample data to coclude that hypertextig tees are more likely to have tried illicit drugs tha are ohypertextig tees. We re 95% cofidet that the differece i proportios (percets) is betwee (0.7%) ad (27.3%). owever: That does t mea at all that textig behavior is a cause of illicit drug use. As we see above, it may well be that the root cause is how may parets a teeager has. There certaily is more i favor of such a explaatio. Aggregated over the whether or ot a hypertexter variable, assessig the effects of paretal presece. The two observed proportios are ad Their differece is The P-value for the test is essetially 0. The 99% CI has bouds give by ± , which gives < p1 p2 < We are 99% cofidet that the proportio of all tees from 1-paret families who have tried illicit drugs is betwee ad higher tha that for tees from 2-paret families. (Betwee roughly 40% ad 70% higher.) owever: This too may ot be iterpreted as causal while the umber of parets variable is certaily more strogly associated with drug use, this does ot imply that the umber of parets is a cause of illicit drug use. What about icome? I a similar way as show above, we might well fid that tees from lower icome families are simultaeously more like to have 1 paret ad to have tried illicit drugs. I short: It is oe thig to establish that two variables are associated. It is aother altogether to establish that chages i a explaatory variable cause a chage i the distributio of the respose variable. From a sigle observatioal study, oe ca ever coclude o the issue of causatio. OMG! Page 6

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