# PSYC 2300-2300L Ch. 12

## 25 terms · Test 2

### correlational research strategy

two or more variables are measured to obtain a set of scores for each individual. the measurements are then examined to identify any patterns of relationship that exist between the variables and to measure the strength of the relationship.

### correlation/correlation coefficient

measure and describe the relationship between two variables

### positive relationship

tendency for two variables to change in the same direction as one variable increases, the other also tends to increase

### negative relationship

tendency for two varibales to change in opposite directions; increases in one variable tend to be accompanied by decreases in the other

### linear relationship

where data points in the scatter plot tend to cluster around a straight line

### monotonic relationship

relationship that is consistently one directional, either consistently positive or consistently negative

### Pearson correlation

measures linear relationships

### Spearman correlation

measures monotonic relationships

### correlation describes 3 characteristics of a relationship

1. direction of relationship (positive/negative)
2. form of the relationship (linear/monotonic)
3. consistency/strength of the relationship (+1.00/-1.00)

### correlational study vs. differential design

c.s.= does not involove manipulating with variables
d.d.= demonstrates a difference between groups

### predictor variable

the first variable

### criterion variable

second variable being explained or predicted

### reliability

evaluates the consistency or stability of the measurements

### validity

evaluates the extent to which the measurement procedure actually measures what it claims to be measuring

### coefficient of determination

obtained by squaring the numerical value of the correlation (s/m/l r= 0.10, 0.30, 0.50)

### 2 limitations of correlational study

1. 3rd-variable problem
2. directionality problem

### primary advantage of correlational study

simply records what exists naturally with no manipulation

### mulitple regression

studyies multivariate relationships while controlling the influence of other, potentially confounding variables

### predictive validity

when scores obtained from a measure accurately predict behavior according to a theory

### concurrent validity

scores obtained from a new measure are directly related to scores obtained from a more established measure of the same variable

### divergent validity

2 different methods to measure 2 different constructs

### test-retest reliability

established by comparing the scores obtained from two successive measurements of the same individuals and cal a correlation between the 2 sets of scores

### parallel-forms reliability

comparing scores obtained by using 2 alternate versions of a measuring instrument to measure same indvs and calc correlation between 2 scores

### inter-rater reliability

degree of agreement between two observers who simultaneously record measurements of a behavior

### split-half reliability

splitting the items on a questionnaire or test in half, computing separate score for each half, then measuring the degree of consistency between the two scores for a group of participants