A researcher believes that traffic fatalities increase when roads are icy and so states with more snow will have more fatalities than other states. Comment on the following methods designed to estimate the effect of snow on fatalities:
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 (Snowit) and adds this regressor to the regressions.