I apologize if this is a very primitive question compared to what is asked here normally. I am looking for how to do the post-hoc tukey test and represent significant differences in letters, numbers, and asterisks similar to how graph as done them. This is an example of a Two-Way ANOVA with the lettering, numbers, and asterisks I want
My graph currently looks like this and I made it in excel. I'm very unfamiliar in how to use R to make this graph, but furthermore to do the post-hoc analysis and then somehow show said symbols on the graph too. I'm finding it very difficult to find a precise answer on youtube or on the internet in general, so I was hoping for some direct advice.
How do I make my Two-Way ANOVA graph look like the example graph? enter image description here
I have tried to manually determine the P-values and then group them by the letters, but I'm finding it difficult how to number bars across treatments.