Results

Use the download.jasp data from Chapter 6 to test whether hygiene levels changed significantly over the three days of the festival.

Conduct a Friedman’s ANOVA because we want to compare more than two (day 1, day 2 and day 3) related samples (the same participants were used across the three days of the festival).

Repeated Measures ANOVA

Within Subjects Effects
Cases Sum of Squares df Mean Square F p
Timepoint 40.267 ᵃ 2 ᵃ 20.134 ᵃ 96.376 ᵃ < .001 ᵃ
Residuals 50.973 244 0.209  
Note.  Type III Sum of Squares
ᵃ Mauchly's test of sphericity indicates that the assumption of sphericity is violated (p < .05).
Between Subjects Effects
Cases Sum of Squares df Mean Square F p
Residuals 115.271 122 0.945  
Note.  Type III Sum of Squares

Descriptives

Descriptives plots

Nonparametrics

We can report our findings as follows:

The hygiene levels significantly decreased over the three days of the music festival,  (2) = 86.54, p < .001. However, pairwise comparisons with Bonferroni adjusted p-values revealed that while hygiene scores significantly decreased between days 1 and 2, pbonf < .001, rrb = 0.89, and days 1 and 3, pbonf < .001, rrb = 0.85, they did not significantly decrease between days 2 and 3, pbonf = .399, rrb = -0.16.
Friedman Test
Factor Χ²F df p Kendall's W
Timepoint 86.535 2 < .001 0.352

Conover Test

Conover's Post Hoc Comparisons - Timepoint
    T-Stat df Wi Wj rrb p pbonf pholm
Day 1 Day 2 10.633 244 329.000 195.000 0.887 < .001 < .001 < .001
  Day 3 9.126 244 329.000 214.000 0.850 < .001 < .001 < .001
Day 2 Day 3 1.508 244 195.000 214.000 -0.158 0.133 0.399 0.133
Note.  Grouped by subject.
Note.  Rank-biserial correlation based on individual signed-rank tests.