A sample of n = 4 scores is selected from a population with ? = 50 and ? = 12 . If the sample mean is M = 56, what is the z-score for this sample mean?

Which of the following is the most accurate statement about gray hair?

a. In many cases, the pigments that cause gray hair are actually toxic to the human body, which is why dying gray hair can actually b. Gray hair is something that all people will inevitably experience, starting at an average of 25 years of age. c. Hair doesn't "turn" gray, but rather stays gray when the natural pigments in hair follicles stop being produced. d. Most people view the graying of hair as a very negative event that signals the end of youth, vitality, and productivity.

Clark and colleagues (Clark, 1969; Clark & Yang, 1972) found that participants reported less pain when treated with acupuncture even though there was no difference in d? between the treatment (acupuncture) and control (no acupuncture) conditions. This suggests that

a. acupuncture has no effect on reports of pain. b. with acupuncture, the participant's decision criterion for reporting pain increased. c. with acupuncture, the participant's decision criterion for reporting pain decreased. d. participants had reduced sensitivity to pain when treated with acupuncture.