topic Re: Blocking in factorial Design in Discussions

Blocking in factorial Design

paul1 — Thu, 08 Jun 2023 20:58:10 GMT

I would like to set up a full factorial 2^4 design with a three level block (48 experiments).

In JMP Pro 13, is there an way to include a blocking variable through DOE>Classical>Screening Design? I see an option under DOE>Custom Design to add a blocking variable.

Thanks.

Re: Blocking in factorial Design

louv — Wed, 29 Mar 2017 01:59:50 GMT

Paul,

I think the Custom Designer gives you what you are after.

Re: Blocking in factorial Design

Dan_Obermiller — Wed, 29 Mar 2017 15:14:55 GMT

Paul,

Lou has given you good advice, Custom Design will do what you ask. I will attempt to briefly answer WHY you can't get what you want from the screening design platform.

Classic screening designs are orthogonal. That means that even the blocks need to be orthogonal, too. There is no way to divide 16 evenly by 3, so you cannot get an orthogonal block. Remember that at this point in the design creation, JMP does not know that you are going to replicate the design 3 times. That is why all of the block sizes are powers of 2 -- that will keep the design orthogonal.

There are ways to "trick" the screening design platform into giving you what you want, but as Lou said, Custom Design will do that without any tricks.

Re: Blocking in factorial Design

paul1 — Wed, 29 Mar 2017 18:33:47 GMT

Hi,

I did end up using Custom Design for this problem. In Lou's answer to an earlier question on Blocking/Confounding the image seemed to show blocking with a screeing design. I am new to JMP but I did not see a way to set up a blocking variable using DOE>Classical>Screening Design, say a 2^4 with 2 blocks of size 8 each. Thanks for your responses.

Re: Blocking in factorial Design

louv — Wed, 29 Mar 2017 19:05:16 GMT

Hi Paul,

Yes you can set up for a blocking factor in the Screening Platform however you are limited to a block size of 2,4 or 8. Your scenario with three blocks drove me to leverage the flexibility of JMP's custom designer.

Here is a screenshot of the Screening Design Catalog of Designs illustrating the block size choices.