On Wed, 23 Feb 2000 19:14:10 GMT, [EMAIL PROTECTED] wrote:
> Programmed a solution in Statistica Basic that transforms the raw data
> into the proper form for the "Logit" tool: codes and [frequency]
> counts. Then, used the Logit tool to fit a curve to the data
> using "maximum likelyhood" prediction method. Looked at the 2D
> function plot and it looked reasonable. However, when I decrease the
> ration of ones to zeros (thus decreasing the probability) at the
> beginning of the data set (time ordered), the function plot is way off
> in the center where there are entirely all ones. Is there a better
> model to use? One that will not go "haywire" when data is changed at
> the beginning or end of the data set?
>
I answered before, but I don't know what you are talking about now.
It sounds like you are discarding a bunch of your data, and that c
consists of selectively discarding one response (the 1's); and then
you are surprised when the model changes. I don't know if you are
dropping too much data, or if a change depends on the nature of what
you drop.
I don't know, even, what you mean by, "beginning or end of the data
set", in this context. When the data are ordered, in a meaningful
way, then that is something that might become a factor --
statistically speaking -- in the analysis.
You might have to find someone to speak to, with your data in hand, in
order to clear up those descriptions.
--
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html
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