I am presently summarizing the results of a two-way ANOVA with a significant interaction in a bar chart. The first factor has four levels and the second factor has two levels. My graph has eight bars with numerous significant pairwise comparisons (as assessed by sequential Bonferroni correction).
I want to put letters above the bars in the chart to indicate the significant differences among my various pairwise comparisons; however, these letters were not provided in my raw output for the ANOVA. Is there a way for SPSS to generate these letters? I have not been able to locate this feature. I can try to generate the letters myself but it will take time and I am likely to make an error along the way.
Any advice for how to present these differences in a bar chart would be greatly appreciated.