8) The analysis is externally valid if A) the statistical inferences about causal effects are valid for the population being studied. B) the study has passed a double blind refereeing process for a journal. C) its inferences and conclusions can be generalized from the population and setting studied to other populations and settings. D) some committee outside the author's department has validated the findings. uence of the excluded variable. D) the OLS estimator no longer exists. 9) All of the following are examples of joint hypotheses with two restrictions on multiple regression coefficients, with the exception of A) H0:12=0 B) H0:3=1 and 4=0 C) H0:2=1 and 3=0 D) H0:1=2 and 1=1