I have temperature data from two different sites, and I want to develop a relationship for temperature between those two sites. In that way, if I have temperature at just one of those sites, I can approximate the temperature at the other site. My question is whether or not a multivariate regression is appropriate here, since each site has the same errors associated with it, and neither site can necessarily be considered the "true" site. So they are both independent variables. Can a multivariate regression be done with only two independent variables, or do I need at least one dependent variable? Is the difference between a multivariate regression and a typical linear regression likely to be significant? And, how would I go about doing a multivariate regression, would I need special software? I'm not terribly familiar with statistical methods, so please dumb down responses as much as possible. Thanks for any help!