Chapter 12

Question 1

Central tendency

Answer 1

A single number or value that attempts to summarize all the data, describing the typical score or where most of the scores fall.

Question 2

Cohen’s d

Answer 2

An effect size estimate that is the standardized mean difference in scores between groups.

Question 3

Correlation coefficient

Answer 3

A statistic that describe how strongly two variables are related to one another, the degree to which they covary.

Question 4

Descriptive statistics

Answer 4

Statistics that describe and summarize the data collected; these include measures of central tendency (ie mean) variability (standard deviation) and covariation (Pearson correlation)

Question 5

Effect size

Answer 5

The magnitude of an effect, either the effect of association or the difference in scores between groups.

Question 6

Frequency polygons

Answer 6

Graphs of frequencies for continues variables, in which the frequency of each score is plotted on the vertical axis and these points are connected by straight line.

Question 7

Multiple correlation

Answer 7

A correlation between a combined set of predictor variables and one criterion variable

Question 8

Criterion variable

Answer 8

The outcome variable that that is being predicted in regression analysis.

Question 9

Multiple regression

Answer 9

An extension of the correlation technique that models the extent to which one or more predictor variables are related to one criterion.

Question 10

Partial correlation

Answer 10

The correlation between two variables with the influence of a third variable statistically controlled.

Question 11

Predictor variable

Answer 11

The variable used to predict changes in the criterion (outcome) variable in a regression analysis.

Question 12

Regression equation

Answer 12

An equation that represents a line drawn to best fit a set of data points, allowing one to predict values of one variable based on another variable.

Question 13

Restriction of range

Answer 13

When only a subset of variables possible values are sampled or observed, which can lead to misleading null or attenuated correlations.

Question 14

Squared correlation coefficient

Answer 14

A correlation coefficient that has been multiplied by itself, resulting in a value that reflects the proportion of variance shared between the two variables. Or percent.

Question 15

Squared multiple correlation coefficient

Answer 15

The proportion of variance in the criterion that can be explained by the combined set of predictors for multiple correlations.

Question 16

Standard deviation

Answer 16

The average deviation of scores from the mean (square root of variance)

Question 17

Variability

Answer 17

The amount of dispersion for scores around some central value.

Question 18

Variance

Answer 18

A measure of the variability of scores about a mean. The variance is calculated by taking the difference between the each score and the group mean, squaring these differences and dividing the sum of these squares by the number of scores.