3.3. Significant differences and post hoc testing
Significant differences identified by the ANOVA were
further investigated through post hoc tests using Tukey’s
HSD. Differences in the square effect (gender) were
identified from the RLS ANOVA, while all other factors
were tested based upon independent square Tukey’s
analyses due to gender-based interactions.
The significant gender-based square effect was examined,
revealing that females experienced lower pressure factor
values than males. There were no significant differences
due to armrest usage for females, though males did
experience a rather slight but statistically significant
difference with armrest usage yielding some reduction in
pressure factor values. Increased (reclined) trunk–thigh
angle was found to significantly reduce pressure factor
values for both males and females (tested separately), as
demonstrated in Fig. 2, which plots pressure factor means
by trunk–thigh angle separately for each gender, and
identifies Tukey’s HSD groupings by letter (means sharing
the same letter are not significantly different, while those
with different letters are). The lines plotted for each series
(gender) in Fig. 2 facilitate identification of gender-based
interaction (non-additivity). Significant differences were
also observed amongst the chairs (tested separately for
each gender). The chairs were also plotted by pressure
factor means separately for each gender as depicted in
Fig. 3. Fig. 3 is also plotted with lines for each gender series
to assist with determination of where non-additivity has
occurred, which was most apparent for chairs 10, 3 and 2.
As with Fig. 2, Tukey’s HSD defined homogenous