Split Plot experiment

Question

Dear Community,

I want to perform a fractional factorial design and I have 5 factors one of them is Hard to change. Using Custom design I got a table with 18 experiments with 4 whole plots. I can not do all the experiments in one day and I am not sure if I will have minor changes from day to day experiments.

I am wondering if it is possible to do a whole run/ Day?

In my previous Designs I often use Blocking since I did not have any Hard to change factors but in this situation, I do not know what to do

Thank you in advance

ELH · Answer

Dear @statman,

1) yes this is what I am doing for the district factor min= 1 and max = 3

2) okay I will do this

my data are attached

thank you in advance

data.jmp

statman · Answer

Some follow=up thoughts:

1. If you are screening, then why do you have a discrete variable with more than 2 levels?  Pick the extremes of the three levels and test those first.

2. If you don't know whether you have day-to-day variation, perhaps you should do directed sampling PRIOR to dong any experimentation.  If you don't understand what the noise is doing, it will be very difficult to use the conclusions from your experiment to extrapolate into the future.

3. I already commented on the hard-to-change factor.

Can you upload your data table so we can look at what you've got and how you did your analysis?

ELH · Answer

Thank you,
- Are all of the factors continuous?
3 continuous and 1 Discrete Numeric 3 levels factor
- What is the model you are predicting?
I want to perform a screening design, main effect, and 2 order interactions
For the day to day variations, I do not know if I will have a variation or not.
The situation is that I have one hard to change factor that can not change levels easily and I will accept any solution to keep it fixed for a certain level of runs.
When I did some preliminary experiment I found that the variation coming from the Whole plot has a negative value and I do not know how to explain this ?
bets regrds