Thank you all very much for your kind replies and valuable comments. I realized that I should have stated my question clearer - next time I will :) I'm trying to design an experiment in which behavioral/neuronal response v.s. stimulus strength curves are to be measured. We know that the tuning curves are sigmoidal/linear, and my question was how I should spread out the sampling points along the stimulus dimension, say 4 or 7 or even more? We've also known that the error-variance, at least for neuronal responses, should be approximately same as mean, the square root of which shouldn't differ much between different independent variable (stimulus strength). Having read all your suggestions, my impression is that in this case, more sampling may not be terribly beneficial in terms of accurately plot the position and shape of the tuning curve. On the other hand, more replicates, especially at one or two data points, will help us a lot in another analysis. I may try to run a simulation that's directly pertinent to our experiment and see what that tells me.
Is there any reference to the power analysis that Richard mentioned? As I said, in our case, we do have some knowledge of the variance terms. Thanks so much again!! Xinmiao . . ================================================================= Instructions for joining and leaving this list, remarks about the problem of INAPPROPRIATE MESSAGES, and archives are available at: . http://jse.stat.ncsu.edu/ . =================================================================
