[Limdep Nlogit List] Survival analysis questions

[Bruce Newbold]

I am dealing with a large, longitudinal data set that follows a population 
over 3 (unequal) interviews, with censored data. My questions are as follows:
    * Are 3 intervals sufficient for using survival analysis techniques 
such as Cox's proportional hazards model?
    * Given that the time intervals are unequal (i.e., responses to the 
survey occur at  6 months, 2 years and 4 years), are some methods more 
appropriate than others?
Please respond to newbold at mcmaster.ca

Thanks in advance,

Bruce Newbold

*****************************
K. Bruce Newbold
Director, McMaster Institute of Environment and Health (MIEH)
Professor, School of Geography and Earth Sciences
McMaster University
1280 Main St. West
Hamilton, ON L8S 4K1

Tel.: 905-525-9140 x27948
Fax.: 905-546-0463
Email: newbold at mcmaster.ca
http://www.science.mcmaster.ca/~geo/faculty/newbold/index.html
http://www.mcmaster.ca/mieh