If an entire population of N = 20 scores is transformed into z-scores, the set of 20 z-scores will have ?X = 0

A researcher is interested in studying aggression. In order to measure aggressiveness, he asks parents of nursery school children to rate how aggressive their child is, on a scale of 1 to 7. In this case, the rating that each parent gives his or her child is a __________________.

a. a psychological construct b. a dependent variable c. an independent variable d. an operational definition

Which of the following is an example of the effects of the proximodistal principle on fine motor development?

A) At first, infants reach with their arms, then they grasp with their fingers. B) First, infants can hold their heads upright, and then they can roll over. C) Infants can put their foot in their own mouth. D) Infants exhibit a number of reflexes, including Moro, stepping, and parachute reflexes.