Appendix A Terms

Question 1

mode

Answer 1

the most frequently occurring score in a distribution

Question 2

mean

Answer 2

the arithmetic average of a distribution, obtained by adding the scores and then dividing by the number of scores

Question 3

median

Answer 3

the middle score in a distribution; half the scores are above it and half are below it

Question 4

range

Answer 4

the difference between the highest and lowest scores in a distribution

Question 5

standard deviation

Answer 5

a measure of score variability based on how much individual scores differ from the mean (technical note: a standard deviation is computed by [1] calculating the deviation of the score from the mean, [2] squaring those deviations, [3] finding their average, and [4] finding the square root of this average)

Question 6

normal curve

Answer 6

(normal distribution) a symmetrical, bell-shaped curve that describes the distribution of many types of data; most scores fall near the mean (68% fall within one standard deviation of it) and fewer and fewer near the extremes

Question 7

correlation coefficient

Answer 7

a statistical measure of the extent to which two factors vary together, and thus of how well either factor predicts the other. Scores go up and down together (as with high school and college GPAs). A negative correlation coefficient indicates that one score falls as the other rises (as in the relationship between self-esteem and depression)

Question 8

regression toward the mean

Answer 8

the tendency for extremes of unusual scores or events to fall back (regress) toward the average

Question 9

statistical significance

Answer 9

a statistical statement of how likely it is that an obtained result occurred by chance