Dear Statalist,
I have a panel of bilateral trade flows that varies across industries and over time. Therefore the data vary across exporters, importers, industries and years.
I am also including
- exporter/sector/year fixed effects
- importer/sector/year fixed effects
- pair/sector fixed effects
- pair/year fixed effects
in addition to my variables of interest (that vary across pairs, sectors and years).
I need to cluster my standard errors but I am unsure about the dimension around which I should cluster. I have tried to cluster around pair/sectors, among other choices, but Stata tells me that my variance matrix is nonsingular.
Is there any standard way of deciding around which dimensions to cluster? Any suggestions?
Many thanks.
Alice.
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
