4.1.2. Test of normality
The normality tests of KolmogoroveSmirnov and the
ShapiroeWilk were used to examine the normality of the data.
However, respondents tend to rate 4 and 5 (helpful to very helpful),
resulting in skewed data. Hence, in subsequent analyses, bootstrapping
is used to handle non-normal distributed data. Bootstrapping
is a re-sampling technique which enables researchers to
draw a conclusion about the characteristics of a population strictly
from the existing sample rather than by making parametric assumptions
about the estimator (Byrne, 2010; Mooney & Duval, 1993).
The bootstrap method with sequential quadratic programming
algorithmwas used to obtain estimates of the standard errors of the
parameters and confidence intervals. The standard error of each
parameter estimate is calculated as the standard deviation of the
bootstrapped estimates of that parameter, then, parameter values from the original data are used as starting values for each bootstrap
sample (Norusis, 2012).