When testing a joint hypothesis, you should use t-statistics for each hypothesis and reject the null hypothesis is all of the restrictions fail. use t-statistic and reject all the hypothesis if the statistic exceeds the critical value. use t-statistics for each hypothesis and reject the null hypothesis once the statistic exceeds the critical value for a single hypothesis. use the F-statistics and reject the hypothesis if the p-value is smaller than 0.05. QUESTION 8 Consider the multiple regression model with two regressors X1 and X2, where both variables are determinants of the dependent variable. You first regress Y on X1 only and find no relationship. However when regressing Y on X1 and X2, the slope coefficient beta with overbrace on top subscript 1 changes by a large amount. This suggests that your first regression suffers from: a. heteroskedasticity.
b. perfect multicollinearity.
c. omitted variable bias.
d. dummy variable trap