In United States v. Eichman, the Supreme Court struck down a statute that prohibited __________

Most people take political action to protect or enhance their economic well-being

Indicate whether the statement is true or false.

When two independent variables in a study produce effects that would not be apparent if each independent variable was manipulated in a separate study, we say that there is

a. no main effect. b. only a measured variable. c. an interaction. d. a planned comparison.