How to code a split plot design in JMP Pro 15

mcbeall08

Hello,

 

I need advice on how to properly model a split-plot design in jmp pro 15. I think it needs to have random effects, so an LME model probably will work best I think?

 

I have three main effects: Temperature(Categorical), Cultivar(Categorical), Cultivar*Temperature.

Response Variable - (Continuous) Germination %

 

The experiment was conducted on (1)thermal gradient table. The cultivars were randomized in each subplot. (It is listed as 1-5 in order, but they are randomized at that level). The whole plot is the temperature. The split-plot would be the cultivars I believe. (See picture below for table layout.)

My model in jmp was going to look like this:

Fixed Effects:
Cultivar

Temperature

Cultivar*Temp

 

Random Effects:
Reps[Tempearture]

 

 

Does this account for the right error terms in jmp?

Mark_Bailey

You should not include Rep in the model. It is automatically used to estimate the error variance. You need a new column called Whole Plot perhaps to indicate when the whole plot factor was reset. This variable will be used to estimate the whole plot variance while the Temperature variable will be used to estimate the fixed effects.

 

It looks like your design has Temperature as very hard to change and Cultivar as hard to change. That is, you did not randomize with one of these two factors. So you might want to select DOE > Custom Design and define these two factors this way. Select the option for nested levels to match what you did. This way will be easier, I think, than starting with a new JMP data table and creating all the data columns and meta-data to get the best analysis.

 

The design you made will unfortunately not support estimating and testing the interaction effect. You need to use a larger design in which you reset the temperature.

 

 

You could alternatively assume that the whole plot variance is zero and remove the Whole Plot random effect from the model, but that is likely not realistic.