The data were analysed by means of factor analysis. To attain the best-fitting structure and correct number of factors, the following criteria were used: eigenvalues >1.0, factor loadings>0.40 and the so-called elbow criterion regarding the eigenvalues. Before conducting the factor analysis, the Kaiser–Meyer–Olkin measure of sampling adequacy (KMO) and Bartlett’s test were conducted to evaluate whether the sample was large enough to perform a satisfactory factor analysis. A KMO value >0.5 indicates that the sample size is adequate for factor analysis