Three-way ANOVA lost DFs

JiYeow

Hello,

I learned JMP in class using "perfect" dataset but now I am trying to use it for my research work by running a three way ANOVA using the attached data. Generally, there are three different factors (Current, HRT and Temp) and I would like to see to sig. effect and interaction of each factor on the result (Inf pH). However, the "Effect Test" from the analysis showed "Lost DFs" instead of p-values. I have a pretty small dataset (33 points) so could this be the problem? 

 

Here is what I've done:

1) Analyze -> Fit Model

2) Insert "Inf pH" as Y variable

3) Insert Current, HRT and Temp as Model Effects with * interaction (I also tried doing 2-way ANOVA using only two factors)

4) Run using "Std Least Squares" as Personality (I tried other personalities as well but did not work)

 

I would really appreciate any inputs on how to work around this dataset, in order to get the "Effect Test" p-value result! Thank you very much!

Ji Yeow

 

 

 

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txnelson

Ji Yeow,

The issue you have is that your effects are confounded with each other.  You really only have 2 groups.  One group has a Current=100, HRT=8 and Temp=10.  The second group has Current=300, HRT=12 and Temp=22.5.  Without having measurements made for the different combinations of Current, HRT and Temp, the analysis can not be performed.  That is, you need to have measurements where Current=100, HRT=8 and Temp=22.5, measurements where Current=100, HRT= 12 and Temp=10, and the other combinations of the 3 factors.  For a "Full Factorial" analysis, you need to have measurements made for each of the possible combinations of the 3 factors.  A "Partial Factorial" analysis could also be run, however, for it to be a valid analysis, the design needs to be be developed using DOE(Desing of Experiments), to make sure the final analysis will be valid.

 

The only analysis that you could do with your current data is a Oneway analysis.  If you chose to use Fit Model, just specify one of the factors.