search for: yearctrty

...t Stata uses, so that things become very clear: *xtprobit s age gender gemeduc gemhinc es_gdppc imf_pop estbbo_m, i(yearctry)* This does exactly what I wish to accomplish in R, ie does the heckman selection equation for the selection variables (seven in my case) based upon the uniqueness of "yearctrty" I have worked weeks on this, kindly help me, I think it is a small issue to fix in the equation, although since I am new to R, I do not exactly know what exactly will fix my problem, so any help will be highly appreciated Thanks -- Dr.Saurav Pathak PhD, Univ.of.Florida Mechanical Engineeri...