Cronbach’s alpha coefficient was used in the reliability analysis of the developed scales:
where s2i is the variance of k individual items, s2sum is the variance of the sum of all items. The formula shows that if the expressions do not give a true result, but only an error, then the variance of the sum will be the same as the sum of the variances of the individual expressions – then α = 0. In a situation where the error is negligible and the results are true, α tends to the value 1.
In other words, in the interpretation of the result, the closer the value of Cronbach’s alpha is to 1 (for social measurements we assume 0.9), the more reliable the given scale is. However, it is assumed that above 0.6 the potential unknown error is no longer significant.