a. The researcher collects data on the average snowfall for each state and adds this regressor (AverageSnowi) to the regressions given in Table 10.1. b. The researcher collects data on the snowfall in each state for each year in the sample (Snow) and adds this regressor to the regressions. 10.8 Consider observations (13, X\") from the linear panel data model 1'}: = XirBi + at + Art + \"in where I: 1, . . . , T; i = 1, . . . , N; and ai + Air is an unobserved individual- specific time trend. How would you estimate 81? 10.9 a. In the xed effects regression model, are the xed entity effects, a5, con- sistently estimated as n > 00 with T fixed? (Hint: Analyze the model with no X 's: K, = al- + um) b. If n is large (say, n = 2000) but T is small (say, T = 4), do you think that the estimated values of ai are approximately normally distrib uted? Why or why not? (Hint: Analyze the model 1,; = al- + uh.)