On Dec 1, 2011, at 2:06 AM, yuying shi wrote:
Dear all, I am doing an ordinal data simulation. I?have a question regarding the cut off values between categories. Suppose I have three categories, if I do regression, there should be two cut off values. I find some simulation code for the ordinal data. However, they usually only generate a uniform random number and compare the probability with the random number.
That's not a good description of what they are doing.
Could any one be so kind to tell me the rational behind it. I don't know why we need a random number rather than just two fixed cut off values.
One way to generate a random categorical variable constrained to three values would just be to take a uniform variate on the interval [0,1] and classify it based on whether which of the three segments it is in for 0 < a < b < 1. This really is not an appropriate question for rhelp so you are advised to submit further such questions somewhere they are solicited such as statsexchange.com.
David Winsemius, MD West Hartford, CT