After an entire week of REM-sleep deprivation, about how many times in one night did volunteers have to be awakened to prevent them from experiencing bouts of REM sleep?

One big factor associated with lower rates of cigarette smoking among adults is

A. age. B. high self-esteem. C. higher level of education. D. caffeine use.

If two variables are positively correlated, then in a scatterplot we should notice that high

values of one variable are associated with __________ values of the other variable. a. low b. high c. intermediate d. random e. extreme