Re: Default Signal to Noise in Power Calculation in JMP DOE platformThe choice of a meaningful signal-to-noise ratio is subjective and depends on the situation. The benefit of S/N is that it is relative, which might be easier, but still requires thought.
If you are suggesting to try different S/N to see the power, that is not a good way. S/N should be determined from subject matter expert. You can't 'solve for it' or optimize it. It represents the minimum effect that is practically important.
Re: Default Signal to Noise in Power Calculation in JMP DOE platformHi Mark, for a typical DOE what's the normal signal to noise we need to apply? Should we use setup different signal to noise for all terms or we can also setup individually. any suggestion how to setup these values? Thank you so much.
Re: Default Signal to Noise in Power Calculation in JMP DOE platformYou can also think of it this way...Since the coefficients are the change in the Y from the intercept for each term in the model, you can't move the entire range because you can only go one direction from the intercept at a time. You can't have both the negative and positive coefficient at the same time.
Re: Default Signal to Noise in Power Calculation in JMP DOE platformThe signal is 2 * 1 (coefficient is half effect because of coding). The noise is 1 (standard deviation in same units). So signal to noise is 2:1/
Re: Default Signal to Noise in Power Calculation in JMP DOE platformIn this case, the signal to noise is 1 or 2 when RMSE =1 and coefficient =1?
Re: Default Signal to Noise in Power Calculation in JMP DOE platformThe coefficient represents the change in Y per unit change in X. The factor range is -1 to +1 on the coded scale, or a range of 2. So the coefficient represents half of the change in Y. Say the coefficient is estimated to be 5. That value represents the change in Y over half the range. The Y would change by 10 over the entire range.
There are five related quantities in hypothesis tests: effect size, random variation, significance, sample size, and power. The signal to noise combines the first two quantities. The larger the ratio, the higher the power for the same significance and sample size. There will be a higher probability of rejecting the null hypothesis when it wrong.
Re: Default Signal to Noise in Power Calculation in JMP DOE platformCould you please elaborate on the last statement, "So the predicted effect is twice the coded estimate of the coefficient." Could you provide an example case, please? I am also a bit confused with power and how it relates to the signal-to-noise ratio and its impact on effect size calculations.
Re: Default Signal to Noise in Power Calculation in JMP DOE platformMark - thanks for clarification. Good to know that what I've been teaching people for a few years is correct! I was getting worried
Re: Default Signal to Noise in Power Calculation in JMP DOE platformYou are correct. The Anticipated RMSE is 1 by default. The Anticipated Coefficient is also 1 by default. The coded factor levels mean that the total effect is the predicted change in the response when the factor changes from -1 to +1. So the predicted effect is twice the coded estimate of the coefficient.
Default Signal to Noise in Power Calculation in JMP DOE platformFor some reason (can't remember why - must be something I picked up a few years ago) I have always assumed in the default Power Calculation in the DOE platform (Power Analysis) with RMSE = 1 and Anticipated Coefficient 1 is calculated for a signal to noise ratio of 2 (ie the signal is defined as twice the size of the Anticipated Coefficient)
Something I have recently seen on a DOE JMP webinar suggests to me that this is wrong and that in fact the Signal = Anticipated coefficient (NOT twice the Anticipated Coefficient) , so the default power is in fact calculated for a signal to noise ratio of 1
Can someone put me straight on this
Many thanks
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