# Tukey test letters

#### Mikegranno

##### New Member
Hello. I've made a two-way ANOVA and Tukey test. I have problems with understanding the index letters. Can somebody help me explain what the system is?

#### hlsmith

##### Less is more. Stay pure. Stay poor.
It may help if you tell us what program you used to generate this output.

#### Mikegranno

##### New Member
Hi, i’ve used Rstudio. And visualized in Excel

#### Dason

##### Ambassador to the humans
Typically for this kind of output the letters put the treatments into groups such that anything within that group isn't statistically significantly different from one another. So there isn't enough evidence that anything in group A is different from anything else in group A. Treatments that don't share any group letters are statistically different from one another though.

For example Temp=5, Location=Ringsted has Index A so it's not different from Temp=5, Location=Solrod but it is different from Temp=10, Location=Gravlev. That's just a single example and I'm playing a bit loose with the language but hopefully it illustrates what that particular encoding is supposed to represent.

#### Mikegranno

##### New Member
Thank you, Dason. In this example I've combined 4 different treatments (Temp = temperature). If I make a two-way ANOVA for Temp = 5 only it says Ringsted-Gravlev and Ringsted-Solrod is different from each other. How do I see that in the index letters?

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