[R] ordinal data simulation

David Winsemius dwinsemius at comcast.net
Thu Dec 1 15:02:50 CET 2011

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

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