3.5. Statistical analysis
The statistical program SPSS 20 was used for analysis. The size of each sample determined the choice of either a parametric or a nonparametric test. Nonparametric tests have been used to compare the results from different occasions, when the number of respondents is low (less than 30) and information on normal distribution is missing (Hinton et al., 2004). The answers of the respondents at most interventions were paired, and the comparisons were analyzed using the Wilcoxon signed-ranks test (B, C, D, and F). The answers from the respondents at the first intervention (A) were not paired. The comparison was conducted using the Mann–Whitney U-test and the Wilcoxon rank sum. The Mann– Whitney U-test, the Wilcoxon signed ranks, and the Wilcoxon rank sum are all nonparametric tests used to identify statistically whether there is a difference among samples based on the ranks of the cases (Hinton et al., 2004). During one intervention (E), the number of respondents was great, and the comparison was conducted using an independent sampled t-test, which compares the two samples based on the mean score (Hinton