Chapter 19 Correlation

Question 1

Biserial (correlation coefficient)

Answer 1

Correlation used where one variable is artificially dichotomous; formed by categorising from an underlying continuous and normal distribution

Question 2

Correlation

Answer 2

A (standardised) measure of relationship of co-variance between two variables

Question 3

Correlation coefficient

Answer 3

Number signifying strength of correlation between two variables

Question 4

Curvilinear correlation

Answer 4

Correlation between two variables with low r value because the relationship does not fit a straight line but a good curve

Question 5

Negative correlation

Answer 5

Correlation where, as values of one variable increase, related values of another variable tend to decrease

Question 6

Positive correlation

Answer 6

Correlation where, as values of one variable increase, related values of another variable tend to increase

Question 7

Correlation strength

Answer 7

Measure of the closeness of the relationship, indicated by a number between 0 and 1 (positive or negative). Strength does not indicate significance.

Question 8

Dichotomous variable

Answer 8

Variable with just two exhaustive values (e.g. male/female)

Question 9

Linearity

Answer 9

Extent to which a relationship between two variables can be represented by a straight line rather than, say, a curved line

Question 10

Pearson’s product-moment correlation coefficient

Answer 10

Parametric measure of correlation

Question 11

Phi coefficient

Answer 11

Measure of correlation between two truly dichotomous variables

Question 12

Point biserial correlation

Answer 12

Measure of correlation where one variable is truly dichotomous and the other is at interval level

Question 13

Range restriction

Answer 13

A selection of cases form a larger potential data set, which has the effect of distorting the true population correlation

Question 14

Scatterplot

Answer 14

Diagram showing the placement of paired values from two variables on a two-dimensional chart

Question 15

Spearman’s rho

Answer 15

Non-parametric, ordinal level measure of correlation; Pearson correlation on ranks of the paired raw scores

Question 16

Variance estimate

Answer 16

Estimate of variance in a variable accounted for by the correlation of another variable (or other variables) with it