I conducted a three-way independent ANOVA. I manipulated the sound of my stimulus to be 1: congruent (KON), 2: incongruent (INK) and 3: no sound at all (control condition). One of my planned comparisons, the incongruent (INK) vs. the congruent (KON) sound is in essence a post-hoc test, isn't it? As, in both cases, I am comparing two levels of my manipulation. Yet, the results I get differ.
Df Sum Sq Mean Sq F value Pr(>F) Manipulation 2 12.34 6.170 2.473 0.0902 . Manipulation: control vs. Experimental 1 9.21 9.206 3.690 0.0580 . Manipulation: INK vs. KON 1 3.13 3.133 1.256 0.2655 Residuals 88 219.54 2.495
Tukey multiple comparisons of means 95% family-wise confidence level
$Manipulation diff lwr upr p adj KON-INK 0.4506173 -0.508031 1.40926557 0.5040074 NS-INK -0.4960317 -1.444847 0.45278399 0.4293551 NS-KON -0.9466490 -1.962296 0.06899754 0.0730128
Pairwise comparisons using t tests with pooled SD
INK KON KON 0.797 - NS 0.648 0.087 P value adjustment method: bonferroni
So what really confuses me is that the difference between KON - INK in case of the planned comparision has a p-value of 0.2655, in case of the Tuckey HSD it has 0.5040074 and in case of the pairwise comparision with bonferroni correction, it has 0.797.
Where are these differences coming from? Or where is the flaw in my logic?