Ocenjevanje zanesljivosti večrazsežnostne lestvice s koeficientom alfa

The purpose of the study was to assess internal consistency by calculating coefficient alpha. It presents the variation in coefficient alpha, depending on questionnaire length and the homogeneity or heterogeneity of the questionnaire. The maximum possible value for coefficient alpha was also calculated by the item elimination method. The study included 99 children aged 10. The children completed The Athletic Coping Skills Inventory - 28 (ACSI-28Smith et al., 1995), which contains seven constructs: coping with adversity, coachability, concentration, confidence and achievement motivation, goal setting and mental preparation, peaking under pressure and freedom from worry. The results confirmed that the values of the alpha coefficient vary depending on the number and composition of items and the sample size. In terms of item structure, homogeneous constructs yielded lower values for the alpha coefficient (in a range from .48 to .61) than the questionnaire with all the constructs (alpha = .79), despite higher inter-item correlations. In terms of the number of items, the longer test generated higher alpha coefficients (alpha= .79) than the shorter test (half-sets of items = .60, .73, .69, .70). A higher overall value (alpha= .83) can be achieved by item elimination.Namen raziskave je bil oceniti notranjo skladnost z izračunavanjem koeficienta alfa. Predstavlja spreminjanje koeficienta alfa odvisno od dolžine vprašalnika ter njegove homogenosti ali heterogenosti. Najvišja možna vrednost za koeficient alfa je bila izračunana tudi po metodi izločanja postavk. Raziskava je vključevala 99 otrok, starih 10 let. Otroci so izpolnjevali The Athletic Coping Skills Inventory - 28 (ACSI-28Smith idr., 1995), ki vsebuje sedem sestavin: obvladovanje stiske, sposobnost biti voden, koncentracija, zaupanje in sprejemanje motivacije, zastavljanje ciljev in miselna priprava, doseganje vrhunca pod pritiskom in osvobojenost skrbi. Rezultati so potrdili, da se vrednosti koeficienta alfa spreminjajo odvisno od števila in sestave postavk in od velikosti vzorca. V smislu strukture postavk so homogene konstrukcije dajale nižje vrednosti za alfa koeficient (v razponu med 0,48 do 0,61) kot vprašalnik z vsemi sestavinami (alfa = 0,79), kljub višjim korelacijam med postavkami. V smislu števila postavk je daljši test generiral višji alfa koeficient (alfa = 0,79) kot krajši test (polovični nabori postavk = 0,60, 0,73, 0,69, 0,70). Višjo skupno vrednost (alfa = 0,83) je mogoče doseči z izločanjem postavk