True or False:

1) ____ The conditional independence assumption (CIA) implies that the explanatory variable is independent from actual outcomes (observed values of the dependent variable) conditional on an adequate set of observed characteristics.

2) ____ Variables measured before the variable of interest was determined are usually "good controls".

3) ____ The "exclusion restriction" imposed on the instrumental variable z implies that z is excluded from the causal model of interest.

4) ____ The panel data estimator that uses deviations from means (time-demeaning) to eliminate the "unobserved effect" will be less efficient than the estimator that applies first differencing when the panel includes more than two periods and the idiosyncratic error is homoscedastic and serially uncorrelated.