When it can be concluded that the independent variable alone brought about the observed changes in the dependent variable, a study can be said to be

Systematic attempts to make inferences about the opinions of large numbers of individuals by carefully sampling and asking questions to a small, randomly assigned sample of the larger population are defined as ______.

a. public opinion surveys b. straw polls c. self-selected listener opinion polls d. exit polls

Which of the following is a risk of a party platform that is too broad?

a. It threatens the two-party system.  b. It makes passing legislation difficult.  c. It creates a coalition with limited voter support.  d. It may find itself marginalized.