Ch12: correlational research strategy

Question 1

What does the correlation coefficient describe?

Answer 1

The MAGNITUDE and DIRECTION of relationships

Question 2

Pearson r is typically correlated for ___ relationships and ranges from __ to ___

Answer 2

Pearson r is typically correlated for LINEAR relationships and ranges from -1 to +1

Question 3

What does the sign on Pearson r indicate?

Answer 3

DIRECTION (not magnitude) of relationships

Question 4

For nonliner relationships, what coefficient would you use?

Answer 4

a Spearman Correlation Coefficient for non-linear monotonic relationships.
For ORDINAL DATA (eg., sex and intelligence)

Question 5

When both sets of data are nominal, what statistical analysis would you use?

Answer 5

Chi-squared test

Question 6

When one variable is nominal and the other is interval/ratio, what correlation results?

Answer 6

a point-biserial correlation

Question 7

to establish a correlation, you need a __ of scores

Answer 7

range

Question 8

What do you use to determine the significance of the correlation coefficient?

Answer 8

a t-test

Question 9

What is R^2?

Answer 9

• coefficient of determination

- proportion of variability in the DV accounted for by the IV

Question 10

For rest-retest reliability, what ccorrelation would you use?

Answer 10

Pearson r

Question 11

For split-half reliability, what correlation would you use?

Answer 11

Spearman-Brown formula

-note: first calculate R, then Spearman-Brown formula

Question 12

The ___ the correlation, the better the split-test reliability

Answer 12

higher

Question 13

What are correlations used for in inter-rater reliability?

Answer 13

Cohen’s Kappa is used

Cohen’s kappa = (%agreement - percent chance) / (1-%chance)

Question 14

What is Cohen’s Kappa?

Answer 14

measure of agreement that attempts to correct for chance

Question 15

Without some correction, measures of inter-rater reliability…

Answer 15

Tend to overestimate the true level of agreement between the raters

Question 16

What does convergent validity seek to answer?

Answer 16

are 2 measures of the same construct correlated?

Question 17

___ validity is seeking to make sure that 2 measures of different constructs are NOT correlated

Answer 17

divergent

Question 18

____ is used to test significance of r value

Answer 18

t-test

Question 19

cyclical functions make it difficult to determine ___ ___

Answer 19

temporal precedence

Question 20

We use ____ to predict scores on one variable based on scores on another variable

Answer 20

REGRESSION

Question 21

In a regression, what is equivalent to the DV and the IV?

Answer 21

DV = criterion variable
IV = Predictor variable

Question 22

Degrees of freedom for t-test on significance of Pearson r value

Answer 22

N-2

Question 23

With 2 variables, what regression do you use?

Answer 23

simple linear regression

Question 24

Regression equations

Answer 24

y = b1x + b0

• where y has a cap (^)
• b1 is the slope
• b0 is the intercept
• like y=mx+b

Question 25

What is the role of the line of best fit in a simple linear regression?

Answer 25

to minimize the distance of each data point from the predicted value

Question 26

T/F: the size of b1 in the simple linear regression equation (slope) tells us about the strength of the relationship

Answer 26

FALSE. b1 tells us the scale, but doesn't say anything about the strength of the relationship -as x increases, by how much does y change?

Question 27

Purpose of a regression equation?

Answer 27

To make predictions based on the line of best fit

Question 28

What does the sign of b1 tell us?

Answer 28

the direction of the relationship

Question 29

Purpose of a multiple regression

Answer 29

to maximize predictive power. | -more variables = more predictive power

Question 30

Multiple regression equation

Answer 30

y = b1x1 + b2x2 +b0

Question 31

How could you maximize predictability in the following example: Likeability is predicted by physical attractiveness of politician

Answer 31

- add in a measure of political affiliation | - more variables = higher predictive power

Question 32

How do you test the significance of regression equations?

Answer 32

by using the standardized beta. - Standardized beta tell you the SIZE OF THE RELATIONSHIP. It tells you the change in SD units. eg. , as x variable changes by 1 SD, by how many SD's does the y variable change? By *insert standardized beta value*

Question 33

What does the correlation of determination (R square) tell you about a regression equation?

Answer 33

The proportion of variability explained by the regression line

Question 34

In an SPSS output, 4 variables to predict murder rate are in a table. The standardized beta for resident population is 0.052 and for burglary rate per 100,000, it's 0.333. For lacency-theft rate per 100,000, its -0.205 and for motor vehicle theft rate per 100,000, it's 0.0507. Explain what this means

Answer 34

- As population increases by 1 SD, murder rate goes up by 0.052 of a SD. This is a VERY WEAK relationship. - A stronger relationship exists with burglary rate (0.333) - as larceny increases by 1 SD, murder rate decreases by 0.205 - as motor theft rate increases by 1 SD, murder rate increases by 0.507 SD. This is our STRONGEST PREDICTOR. Its significance (p value) is <0.001.

Question 35

If the significance for resident population is 0.576, what does this tell us?

Answer 35

that resident population is not a significant predictor of murder rates

Question 36

Correlation, simple linear regression or multiple regression? For: A local gelati store tracks the number of bowls they sell and the daily high temperature each day for several weeks so they can budget and stock for next summer.

Answer 36

Simple linear regression, because there are 2 variables (one PREDICTING and one criterion)

Question 37

Correlation, simple linear regression or multiple regression? For: Researchers are interested in determining the relationship between death anxiety and religiosity

Answer 37

Correlation

Question 38

Correlation, simple linear regression or multiple regression? For: A university wants to know how accurately scores on each sub-component of the GRE can determine the success of a graduate student.

Answer 38

Multiple regression. PREDICTING future success based on multiple subcomponents of the GRE

Question 39

What kind of reliability analyses can you run with correlations?

Answer 39

- test-retest reliability - split-half reliability - inter-rater reliability

Question 40

What kind of validity analyses can you run with correlations?

Answer 40

- Convergent | - Divergent validity