GP03,Here is a simple example in the context of modeling long run home prices. Let's conjecture that there is a long run relationship between income and home prices. We have monthly data for the 50 US states from Jan 1980 to Dec 2008. The regression model is of the formP(t,i) = alpha + beta(i) Y(t,i) + e(t,i) for i = 1,2...50 and t = 1,..,348Note: if I am not mistaken, we have 29 years of data, so 29 X 12 = 348 monthly observations.Here are the two dimensions of the data:1. Time series - for every state we have a time series of home prices and state income2. Cross Section - for every point in time, t, we have home prices and state income across 50 states.To allow for the fact that there are differences across states, you may want to allow each state to have a separate intercept, i.e. the model isP(t,i) = alpha(1)*D(1) + ... + alpha(50)*D(50) + beta(i) Y(t,i) + e(t,i)In the above regression, we are allowing each state to have its own intercept and own slope parameter, so it boils down to OLS on each separate state. In a panel regression, we may want assume that beta is the same across states, so instead we use the modelP(t,i) = alpha(1)*D(1) + ... + alpha(50)*D(50) + beta Y(t,i) + e(t,i)i.e. we got rid of the subscript i on beta. This should get you started. As someone else mentioned, you may want to google for panel regression. There is a decent primer athttp://
www.nyu.edu/its/pubs/connect/fall03/yaffee_primer.html