Hi @miggledee,

I have a different opinion on your topic.

If you have only two factors and you are interested in the impact of the different ratios on the response, then you only have one factor to consider in your study, which is the factor ratio A/B, as A and B are not independant.

You can then define several levels depending on the precision needed, for example 0, 0.25, 0.5, 0.75 and 1, and add replicates to have robust analysis and interpretation of your results. Make sure to randomize the order in which you realize the tests (even if you only have one factor), to make sure the ratio levels may not be correlated to external nuisance factor (temperature, humidity, day of the week, ...).

Here is a possible design you can create with Custom Design platform :

If you have more than two factors, then the documentation provided by @Ben_BarrIngh about mixture designs can help you.

Hope this answer may help you,

Victor GUILLER

L'Oréal Data & Analytics

"It is not unusual for a well-designed experiment to analyze itself" (Box, Hunter and Hunter)