In order to estimate the average (mean) weight of all professional football players, an investigator determines the weight of the "Dallas Cowboy" players. The Dallas Cowboys are a _________

In most psychology experiments a research finding is considered to be statistically significant if the

a. hypothesis was supported. b. participants were randomly assigned. c. result would occur no more than 5 percent of the time by chance. d. independent variable changed substantially during the experiment.

In the United States today, about what percent of grandparents are raising their grandchildren?

a. about 1% b. about 3% c. about 11% d. about 23%