In SPSS, should you change the significance level for One way ANOVA post-hocs? When running a one-way ANOVA, selecting "Post-hoc" and ticking "Bonferroni":

There is a box at the bottom which says "significance level" and the default is 0.05.

My question is: should I leave the default value (assuming SPSS adjusts accordingly) or change the value to 0.05/k (k groups)?
Leave it at 0.05 . SPSS corrects it properly. Only when you want to test with different alpha's (.10 or 0.01 e.g.) you should change it.