A 360 Degree Feedback Model for Performance Appraisal Based on Fuzzy AHP and TOPSIS

Transcription

1 Iteratoal Joural of Ecooy, aaeet ad Socal Sceces, () Noveber 03, Paes: TI Jourals Iteratoal Joural of Ecooy, aaeet ad Socal Sceces ISSN A 360 Deree Feedback odel for Perforace Apprasal Based o Fuzzy AHP ad TOPSIS Reza Avazpour, Elha Ebrah, ohaad Reza Fath 3.S of aaeet, Faculty of Hua Sceces, Shahed Uversty, Tehra, Ira. PhD Caddate of Hua Resource aaeet, Uversty of Tehra, Tehra, Ira. 3 PhD Caddate of Idustral aaeet, Uversty of Tehra, Tehra, Ira. A R T I C L E I N F O Keywords: Perforace Apprasal 360 Deree Feedback Fuzzy Sets AHP TOPSIS A B S T R A C T Perforace apprasal (PA) whch s a process used by the frs to evaluate ther eployees effcecy ad productvty, was tally carred out by the supervsors. Recetly authors cosder PA as a evaluato process based o the opo of dfferet assessors such as superors, peers, subordates ad the eployees theselves. As assessors have dfferet kowlede about the evaluated eployee, ther dfferet opos could be a ore exact udet. I addto, as the subectve ad ucerta PA processes requre lustc ters, ths study proposes a fuzzy hybrd ultple crtera decso ak approach wth cobato of dfferet assessors' opos, apply fuzzy AHP ethod for deter the wehts of crtera ad us TOPSIS techque for rak eployees order to establsh the hua resources polcy. Ipleet ths approach a real case (a Iraa copay the feld of electrc power ad eery dustry) verfes the applcablty of the proposed fraework. 03 It.. eco. aa. soc. sc. All rhts reserved for TI Jourals.. Itroducto Hua resource aaeet (HR) has eered as a portat dscple that s used ay felds. It has becoe a stratec tool for ost orazatos today's hhly copettve evroet ad Perforace apprasal (PA) s see as oe of the ost crtcal HR tools (aohara, uraldhara, & Deshukh, 0). PA s a foral orazatoal process carred out o systeatc bass to provde a coparso betwee the dvdual or roup perforace based o obectve or subectve eleets (Gareco, Caruat, Sebastao, & Al Ta, 0). It s a evaluatve process by whch aaers rate eployees ad delver feedback to the accord to ther perforace. Theoretcally, PA s put wth the larer real of perforace aaeet ad thus t should focus o perforace proveet. However addto to perforace proveet, PA ay have ay other oals ad otves such as tra, successo pla, pay for perforace ad etc. (Spece & Keep, 0). Ufortuately, the applcato of perforace apprasal systes (PASs) s ether always sooth, or ecessarly productve. It s wdely beleved that PASs do ot always deostrate hh levels of accuracy ad they are ot readly accepted by users (Gareco et al., 0). Oe of the portat PA accuraces s related to ths fact that oe perso s assesset of aother dvdual caot be free of bases. Thus t s ecessary to et ultple assessets for a ore obectve evaluato. ult-source feedback systes also kow as 360 deree apprasal are a ood way to overcoe ths proble. The opos of dfferet assessors such as superors, peers, subordates are ore relable tha oe perso s udet (eeaksh, 0). Aother dffculty of PA process s related to the subectve udets of the assessors. I fact ay stuatos, dvduals prefer to express ther feels us verbal expresso. Fuzzy lustc odels pert traslato of verbal expressos to uercal oes, thereby deal quattatvely wth the expresso of the portace of each crtero ad rak eployees based o the (aohara et al. 0). Ths paper tres to elate the above ltatos of tradtoal ethods of PA by suppos a 360 deree feedback odel based o the FAHP ad TOPSIS ethods. I ths reard, frst the crtera whch are sutable for the purpose of PA the case copay are selected throuh a coprehesve survey of the relevat lterature. The fuzzy AHP ethod s the appled to detere wehts of these crtera based o the experts' opos. Fally TOPSIS ethod s used order to rak soe of the eployees whch are work for the case study copay as the alteratves. Rak outcoes ca be used for the purpose of sort eployees order to establsh the hua resources polces such as prooto ad cetves. The reader of ths paper s orazed as follows. The ext secto deals wth the lterature revew ad s followed by the ethodoloy for the proposed PA odel, whch apples Fuzzy AHP ethod for weht the crtera ad TOPSIS ethod for rak the alteratves. Subsequetly, a real case applcato of the prevous ethodoloes s descrbed. The results ad coclusos are the preseted. Correspod author. Eal address: [email protected]

2 970 Reza Avazpour et al. Iteratoal Joural of Ecooy, aae et ad Socal Sc eces, () Noveber 03. Lterature Revew.. Perforace Apprasal ad Its Related Idcators The perforace evaluato process ofte volves decso ak probles wth a coplex process whch ultple requreets ad ucerta codtos have to be take to cosderato sultaeously. As these assessets are ofte requred to deal wth ucertaty, subectve ature ad precse data, ult-crtera Decso ak (CD) ethods are sutable for copar all alteratves based o ther related raks (Kuo & La, 0). A wde rae of studes have detfed crtera whch play a portat role pleet successful PA orazatos. Scheeer, Beatty ad Bard (986), cosdered PA as the assesset of three areas aely results, behavors, ad persoal characterstcs. Each dctates a specfc type of apprasal forat based o copetecy or ob-related behavor. Gareco, et al. (0) pled to four factors aely Productvty, cotet, Behavor ad persoal characterstcs as the a areas of PA. -pe, Xao-hu ad X a (0) obtaed a four layer syste aely Persoal Qualtes, Tea Sprt, Work Atttude ad Work Perforace as the al factors of PA. Other studes have detered a wde rae of factors as the a PA crtera accord to ther case studes (see e.., aohara et al. 0; Kabak, Burao lu, & Kazaço lu, 0). The a factors of ths study were chose throuh the related lterature ad by hav dscussos wth the aaers, supervsors ad represetatves of eployees the case study copay. The a crtera ad ther related sub-crtera whch are used ths study are show Table. Table. Perforace apprasal crtera a Crtera Sub-crtera Referaces persoal characterstcs Kowlede Ablty to Lear Iovato Proble-solv Adaptablty Decso ak ablty Eotoal stablty -pe, et al. (0); Gareco, et al. (0); oo, Lee ad L (00); Taora ad Gao (009); aohara, et al. (0); Abraha, Kars, Shaw ad ea (00); Kabak, et al. (0); Dursu ad Karsak (00) Iter-persoal relatos Work atttudes Work results Cooperato Tea work Tea Loyalty Coucato Be resposble otvato Dscple cotet Accuracy Effcecy Rapdty Copleteess of assets oo, et al. (00); Gareco, et al. (0); Taora ad Gao (009); Abraha et al. (00); -pe, et al. (0); aohara, et al. (0); Chlto ad Hardrave (004) Gareco, et al. (0); Taora ad Gao (009); -pe, et al. (0) oo, et al. (00); Gareco, et al. (0); Taora ad Gao (009); -pe, et al. (0);.. The 360 Deree Perforace Apprasal Typcally, perforace apprasals have bee lted to a feedback process betwee eployees ad ther superors. Wth the creased focus o teawork, eployee developet ad custoer servce, the ephass has shfted to eployee feedback fro the full crcle of sources (eeaksh, 0). Ths ult-source feedback syste whch s called 360 deree feedback ca clude supervsors, collaborators, colleaues, subordates, eployee theselves ad outsders lke custoers. The 360 deree apprasal syste (see Fure ) presets soe advataes wth coparso wth the tradtoal systes. Accord to Adrés, García-Lapresta ad Gozález-Pachó (00), soe of the 360 deree apprasal syste's advataes are as below: ore extesve due to teral evaluato whch collects forato fro dfferet pots of vew Reduc the bas ad preudce because of the forato collect fro several people, ot ust oe Ecoura the Hua Resources Departet to establsh polces of teral selecto ore clearly based o the results of the evaluato process Def tra ad developet plas for eployees based o dvdual ad roup perforace apprasal results allow copaes to detfy successful people ore easly wth the a of reforc, recoz ad ecoura ther results I order to overcoe the crtques assocated wth the tradtoal PA process ad to adopt the advataes of the teral evaluato, we propose a 360-deree apprasal odel where dfferet sets of assessors have to evaluate eployees accord to dfferet crtera. 3. Research ethodoloy 3.. Research Fraework The purpose of ths paper s develop a perforace apprasal fraework where there are dfferet sets of assessors tak part the evaluato process. I ths fraework whch s based o the fuzzy ultple crtera decso ak approach, the PA crtera are be wehted throuh fuzzy AHP ethod ad the eployees are raked based o ths wehed crtera throuh TOPSIS ethod. The overall four-step fraework of the study s show Fure.

3 A 360 Deree Feedback odel for Perforace Apprasal Based o Fuzzy AHP ad TOPSIS Iteratoal Joural of Ecooy, aaeet ad Socal Sceces, () Noveber Fure. 360-deree apprasal Fure. Research fraework 3.. Fuzzy Sets ad Fuzzy Nubers Fuzzy set theory, whch was troduced by Zadeh (965) to deal wth probles whch a source of vaueess s volved, has bee utlzed for corporat precse data to the decso fraework. A fuzzy set A ca be defed atheatcally by a ebershp fucto ( X ), whch asss each eleet x the uverse of dscourse X a real uber the terval [0,]. A traular fuzzy A uber A ca be defed by a trplet (a, b, c) as llustrated Fure 3. 0 A B C Fure 3. A traular fuzzy uber A The ebershp fucto ( X ) s defed as A x a b a x c ( X ) A b c 0 a x b b x c otherwse ()

4 97 Reza Avazpour et al. Iteratoal Joural of Ecooy, aae et ad Socal Sc eces, () Noveber 03 Basc arthetc operatos o traular fuzzy ubers A = (a,b,c ), where a b c, ad A = (a,b,c ), where a b c,ca be show as follows: Addto: A A = (a + a,b + b,c +c ) () Subtracto: A A = (a - c,b - b,c a ) (3) ultplcato: f k s a scalar K A = ( ka, kb, kc ), ( kc, kb, ka ), k 0 k 0 A A (a a,b b,c c ), f a 0, a 0 (4) a c Dvso: A Ø A (,, ), b b c a f a 0, a 0 (5) Althouh ultplcato ad dvso operatos o traular fuzzy ubers do ot ecessarly yeld a traular fuzzy uber, traular fuzzy uber approxatos ca be used for ay practcal applcatos (Kaufa et al. 988). Traular fuzzy ubers are approprate for quatfy the vaue forato about ost decso probles clud persoel selecto (e.. rat for creatvty, persoalty, leadershp). The prary reaso for us traular fuzzy ubers ca be stated as ther tutve ad coputatoal-effcet represetato (Karsak, 00). A lustc varable s defed as a varable whose values are ot ubers, but words or seteces atural or artfcal lauae. The cocept of a lustc varable appears as a useful eas for provd approxate characterzato of pheoea that are too coplex or ll-defed to be descrbed covetoal quattatve ters (Zadeh, 975) Fuzzy Aalytc Herarchy Process Frst proposed by Thoas L. Saaty (980), the aalytc herarchy process (AHP) s a wdely used ultple crtera decso-ak tool. The aalytc herarchy process, sce ts veto, has bee a tool at the hads of decso akers ad researchers, beco oe of the ost wdely used ultple crtera decso-ak tools (Vadya et al. 006). Althouh the purpose of AHP s to capture the expert s kowlede, the tradtoal AHP stll caot really reflect the hua thk style (Kahraa et al. 003). The tradtoal AHP ethod s probleatc that t uses a exact value to express the decso aker s opo a coparso of alteratves (Wa et al. 007). Ad AHP ethod s ofte crtczed, due to ts use of ubalaced scale of udets ad ts ablty to adequately hadle the heret ucertaty ad precso the parwse coparso process (De, 999). To overcoe all these shortcos, fuzzy aalytcal herarchy process was developed for solv the herarchcal probles. Decso-akers usually fd that t s ore accurate to ve terval udets tha fxed value udets. Ths s because usually he/she s uable to ake hs/her preferece explctly about the fuzzy ature of the coparso process (Kahraa et al. 003). The frst study of fuzzy AHP s proposed by Va Laarhove ad Pedrycz (983), whch copared fuzzy ratos descrbed by traular fuzzy ubers. Buckley (985) tated trapezodal fuzzy ubers to express the decso aker s evaluato o alteratves wth respect to each crtero Cha (996) troduced a ew approach for hadl fuzzy AHP, wth the use of traular fuzzy ubers for par-wse coparso scale of fuzzy AHP, ad the use of the extet aalyss ethod for the sythetc extet values of the par-wse coparsos. Fuzzy AHP ethod s a popular approach for ultple crtera decso-ak. I ths study the extet fuzzy AHP s utlzed, whch was orally troduced by Cha (996). Let X = {x, x, x 3,..., x } a obect set, ad G = {,, 3,..., } be a oal set. The, each obect s take ad extet aalyss for each oal s perfored, respectvely. Therefore, extet aalyss values for each obect ca be obtaed, wth the follow ss:, Where follows:,...,, =,,, (=,, 3,, ) are all traular fuzzy ubers. The steps of the Cha's (996) extet aalyss ca be suarzed as Step : The value of fuzzy sythetc extet wth respect to the th obect s defed as: S Where deotes the exteded ultplcato of two fuzzy ubers. I order to obta extet aalyss values for a partcular atrx such that, l,, u (6), we perfor the addto of (7)

5 A 360 Deree Feedback odel for Perforace Apprasal Based o Fuzzy AHP ad TOPSIS Iteratoal Joural of Ecooy, aaeet ad Socal Sceces, () Noveber Ad to obta, we perfor the fuzzy addto operato of = l, u The, the verse of the vector s coputed as, ( =,,,) values such that,, (8) (,, ) Where u,, l >0 u l (9) Fally, to obta the S, we perfor the follow ultplcato: S l l, u, (0) u Step : The deree of possblty of = (l,,u ) = (l,,u ) s defed as V ( ) = sup[( ( x), ( y))] Ths ca be equvaletly expressed as, V ( ) ht( () ) ( d ) ( 0 l u u ) ( l ) f fl u otherwse Fure 4 llustrates V ( ) for the case d for the case < l < u <, where d s the abscssa value correspod to the hhest crossover pot D betwee ad,to copare ad, we eed both of the values V ( ) ad V ). ( () V( ) D 0 L L d U U Fure 4. The tersecto betwee ad (Cha 996) Step 3: The deree of possblty for a covex fuzzy uber to be reater tha k covex fuzzy ubers (=, k) s defed as V,,..., ) V ( ), =,,,k ( k Step 4: Fally, W=( V( s s k ), V( s s k ),., V( s s k )) T, s the weht vector for k =,,.

6 974 Reza Avazpour et al. Iteratoal Joural of Ecooy, aae et ad Socal Sc eces, () Noveber TOPSIS ethod The TOPSIS ethod s proposed Che ad Hwa (99), wth referece to Hwa ad Yoo (98). The basc prcple s that the chose alteratve should have the shortest dstace fro the deal soluto that axzes the beeft ad also zes the total cost, ad the farthest dstace fro the eatve-deal soluto that zes the beeft ad also axzes the total cost (Oprcovc ad Tze, 003). The TOPSIS ethod cossts of the follow steps: Step : Calculate the oralzed decso atrx. The oralzed value r s calculated as r X / X,, (3) Step : Calculate the wehted oralzed decso atrx. The wehted oralzed value v s calculated as v w r, (4), Where w s the weht of the th crtero, ad W Step 3: Detere the deal ad eatve-deal soluto. A { v,..., v } {(ax v C ),( v C )} (5) h c A { v,..., v } {( v C h ),(ax v C c )} (6) where Cb s assocated wth beeft crtera ad Cc s assocated wth cost crtera. Step 4: Calculate the separato easures, us the -desoal Eucldea dstace. The separato of each alteratve fro the deal soluto s ve as S v v, (7) Slarty, the separato fro the eatve-deal soluto s ve as S v v, (8) Step 5: Calculate the relatve closeess to the deal soluto. The relatve closeess of the alteratve A wth respect to A s defed as RC I S S S, Step 6: Rak the preferece order. The dex values of RC I le betwee 0 ad. The larer dex value eas the closer to deal soluto for alteratves. (9) 4. Eprcal Aalyss The case of ths study s a Iraa copay whch s actve the feld of electrc power ad eery. Its sso s aa the assets of the copay the electrc power dustry, lead actvtes for the purpose of supply relable ad ecoocal electrcty for all sectors of cosupto, aaeet ad supervso o stallato ad operato of facltes ad eter to trasactos of electrcty. The case study copay teds to carry out ts perforace apprasal process by eas of the prevously proposed odel. The copay eed to effcetly qualfy eployees to detere the level of effcecy of each eployee order to develop Hua Resources polces ad to acheve a effectve persoel aaeet. For ths purpose, the copay s carry out a 360-deree assesset over ther eployees of the proect pla departet whch volves evaluatos fro supervsors, colleues, subordates ad eployees theselves. There are fve eployees work ths departet as proect pla experts. These fve eployees are be evaluated based o the crtera show Table. Thus we have fve eployees (as alteratves) whch are o to evaluate based o four roups of crtera by four assessors. I ths paper, the wehts of crtera are calculated us Fuzzy AHP, ad these calculated weht values are used as TOPSIS puts. The, after TOPSIS calculatos, evaluato of the alteratves ad selecto of best perso s realzed.

7 A 360 Deree Feedback odel for Perforace Apprasal Based o Fuzzy AHP ad TOPSIS Iteratoal Joural of Ecooy, aaeet ad Socal Sceces, () Noveber Fuzzy AHP I Fuzzy AHP ethod, we detere the wehts of each factor by utlz par-wse coparso atrxes. We copare each factor wth respect to other factors. You ca see the par-wse coparso atrx for rak of these factors Table. Table. Fuzzy par-wse coparso atrx C C C 3 C 4 C (.00,.00,.00) (.00,.00,3.00) (0.33,0.50,.00) (.00,3.00,4.00) C (0.33,0.50,.00) (.00,.00,.00) (.00,3.00,4.00) (.00,.00,3.00) C 3 (.00,.00,3.00) (0.5,0.33,0.50) (.00,.00,.00) (0.33,0.50,.00) C 4 (0.5,0.33,0.50) (0.33,0.50,.00) (.00,.00,3.00) (.00,.00,.00) After for fuzzy par-wse coparso atrx, we calculate the weht of crtera. The weht calculato detals are ve below. The value of fuzzy sythetc extet wth respect to the th obect ( =,,3,4) s calculated as S = (4.33, 6.50, 9.00) (0.03, 0.05, 0.07) = (0.5, 0.3, 0.65) S = (4.33, 6.50, 9.00) (0.03, 0.05, 0.07) = (0.5, 0.3, 0.65) S 3 = (.58, 3.83, 5.50) (0.03, 0.05, 0.07) = (0.09, 0.9, 0.40) S 4 = (.58, 3.83, 5.50) (0.03, 0.05, 0.07) = (0.09, 0.9, 0.40) The the V values calculated us these vectors are show Table 3. Table 3. V values result ( V) S S S 3 S 4 S - S - S S Thus, the weht vector fro Table 3 s calculated ad oralzed as W t = ( , , , ) TOPSIS The wehts of crtera are calculated by fuzzy AHP up to ow, ad the these values ca be used TOPSIS. Accord to TOPSIS ethodoloy, we obtaed wehted oralzed decso atrx that ca be see Table 4. Table 4. Wehted oralzed decso atrx C C C 3 C 4 A A A A A W By follow TOPSIS procedure steps ad calculatos, the rak of persos are aed. The results ad fal rak are show Table 5. Table 5. Fal evaluato of the alteratves Persos S l S l RC I A A A A A Accord to Table 5, A s the best perso ao other persos ad other persos raked as follow: A >A >A 4 >A 5 >A 3.

8 976 Reza Avazpour et al. Iteratoal Joural of Ecooy, aae et ad Socal Sc eces, () Noveber Coclusos Hua resource aaeet has eered as a portat dscple that s used ay felds. It has becoe a stratec tool for ost orazatos today's hhly copettve evroet ad Perforace apprasal s see as oe of the ost crtcal HR tools. The purpose of ths paper s develop a fraework based o the fuzzy ultple crtera decso ak approach to detfy the best Perso. Frst the crtera are recozed. Secod the fuzzy AHP s appled to detere wehts of crtera. Fally TOPSIS ethod s used order to rak the persos. Accord to result, A s the best perso ao other persos. Refereces [] Abraha, S., Kars, L., Shaw, K., & ea,. (00). aaeral copeteces ad the aaeral perforace apprasal process. Joural of aaeet Developet, 0(0), [] Adrés, R., García-Lapresta, J., & Gozález-Pachó, J. (00). Perforace apprasal based o dstace fucto ethods. Europea Joural of Operatoal Research, 07, [3] Buckley, JJ.(985). Fuzzy herarchcal aalyss. Fuzzy Sets Syst 7: [4] Cha, DY.(996). Applcatos of the extet aalyss ethod o fuzzy AHP. Europea Joural of Operatoal Research, 95: [5] Chlto,., & Hardrave, B. (004). Assess Iforato Techoloy Persoel: Toward A Behavoral Rat Scale. The DATA BASE for Advaces Iforato Systes, 35(3), [6] De, H.(999). ultcrtera aalyss wth fuzzy par-wse coparso. It J Approx Reaso :5 3. [7] Dursu,., & Karsak, E. (00). A fuzzy CD approach for persoel selecto. Expert Systes wth Applcatos, 37, [8] Gareco, A., Caruat, A., Sebastao, A., & Al Ta, H. (0). War outsde, ceasefre sde: A aalyss of the perforace apprasal syste of a publc hosptal a zoe of coflct. Evaluato ad Prora Pla, 35, [9] Hwa,.C.L ad Yoo, K. (98). ultple Attrbutes Decso ak ethods ad Applcatos, spr, New York. [0] Kabak,., Burao lu, S., & Kazaço lu, Y. (0). A fuzzy hybrd CD approach for professoal selecto. Expert Systes wth Applcatos, 39, [] Kaufa, A., ad Gupta,.. (988). Fuzzy atheatcal odels eeer ad aaeet scece. Asterda: North-Hollad. [] Karsak, E. E. (00). Dstace-based fuzzy CD approach for evaluat flexble aufactur syste alteratves. Iteratoal Joural of Producto Research 40(3), [3] Kahraa, C., Cebec, U., Uluka, Z. (003). ult-crtera suppler selecto us fuzzy AHP. Lost If aa 6(6): [4] Kuo,., & La, G. (0). A soft coput ethod of perforace evaluato wth CD based o terval-valued fuzzy ubers. Appled Soft Coput,, [5] aohara, T., uraldhara, C., & Deshukh, S. (0). A coposte odel for eployees perforace apprasal ad proveet. Europea Joural of Tra ad Developet, 36(4), [6] eeaksh, G. (0). ult source feedback based perforace apprasal syste us Fuzzy loc decso support syste. Iteratoal Joural o Soft Coput, 3(), [7] -pe, X., Xao-hu, Z., & X a, D. (0). odel of Eeer R&D Staff Perforace Apprasal odel Based o Fuzzy Coprehesve Evaluato. Systes Eeer Proceda, 4, [8] oo, C., Lee, J., & L, S. (00). A perforace apprasal ad prooto rak syste based o fuzzy loc: A pleetato case ltary orazatos. Appled Soft Coput, 0, [9] Oprcovc. S ad Tze. G.H. (003). Coprose soluto by CD ethods: a coparatve aalyss of VIKOR ad TOPSIS, Europea Joural of Operatoal Research 56 (),pp [0] Saaty, T. L. (980). The aalytc herarchy process. New York: cgraw- Hll. [] Scheeer, C., Beatty, R., & Bard, L. (986). Creat a perforace aaeet syste. Tra ad Developet Joural, 40(5), [] Spece, J., & Keep, L. (0). Coscous rat dstorto perforace apprasal: A revew, coetary, ad proposed fraework for research. Hua Resource aaeet Revew,, [3] Steveso, WJ. (993). Producto / operatos aaeet, 4th ed. Rchard D. Irw Ic., Hoewood. [4] Taora, R., & Gao, J. (009). Idetfy acceptable perforace apprasal crtera: A teratoal perspectve. Asa Pacfc Joural of Hua Resources, 47(), 0-5. [5] Vadya, OS, Kuar, S.(006). Aalytc herarchy process: a overvew of applcatos. Europea Joural of Operatoal Research, 69: 9. [6] Va Laarhove, PJ, Pedrcyz, W. (983). A fuzzy exteso of Saaty s prorty theory. Fuzzy Sets Syst :9 4. [7] Wa, YJ, Lee, HS. (007). Geeralz TOPSIS for fuzzy ultcrtera roup decso ak. Coput ath Appl 53: [8] Zadeh, L. A. (975). The cocept of a lustc varable ad ts applcato to approxate reaso-i. Iforato Sceces, 8(3), [9] Zadeh, L. A. (965). Fuzzy sets. Iforato ad Cotrol, 8(3),