Module 10: Multivariate Statistics

Question 1

What is linear regression used to determine?

Answer 1

A straight line fit to the data that minimizes deviations from the line

Question 2

What other word is regression used synonymously with?

Answer 2

Correlation

Question 3

When are multivariate statistical methods used?

Answer 3

When there are three or more variables of interest

Question 4

What is simple linear regression?

Answer 4

One IV is used to predict one DV

Question 5

What levels of measurement should both the IV and DV in a simple linear regression be?

Answer 5

Interval or ratio level (continuous)

Question 6

Because correlation between 2 variables is rarely perfect what time of regression is used to improve predictions of the DV by including multiple IVs?

Answer 6

Multiple linear regression

Question 7

What levels of measurement should both the IV and DV in a multiple linear regression be?

Answer 7

Interval or ratio level (continuous)

Question 8

The R value in multiple linear regression represents what?

Answer 8

The multiple correlation coefficient or the strength of the relationship between multiple IVs
0.00-1.00

Question 9

R(squared) represents:

Answer 9

The proportion of variance in DV accounted for by simultaneous impact of all IVs

Question 10

To equally compare variables in multiple linear regression variables are transformed into standard scores so they can be equally compared, these standardized regression coefficients are called:

Answer 10

Beta weights

Question 11

3 strategies for entering predictor variables into regression equations include:

Answer 11

1. Simultaneous
2. Hierarchal
3. Stepwise

Question 12

How is the simultaneous strategy of entering predictor variables into the regression equation executed?

Answer 12

All variables are entered into the regression equation at the same time. This is used when there is no basis for considering any particular predictor as causally prior to another

Question 13

How is the hierarchical strategy of entering predictor variables into the regression equation executed?

Answer 13

Entering predictors into the equation in a series of steps controlled by the researcher based on theoretical considerations.

Question 14

How is the stepwise strategy of entering predictor variables into the regression equation executed?

Answer 14

Predictor variables are entered into the regression equation in a stepwise fashion using statistical criteria or power.

Question 15

What are general sample size guidelines?

Answer 15

At least 50 ppl + an additional 8ppl/variable

Question 16

What are general sample size guidelines used with simultaneous or hierarchical strategies?

Answer 16

At least 20ppl/variable

Question 17

What are general sample size guidelines used with stepwise strategies?

Answer 17

At least 40ppl/variable

Question 18

What is the role of logistic regression?

Answer 18

Odds ratio, predicts the likelihood of something happening

Question 19

What levels of measurement are the IV and DV in a logistic regression?

Answer 19

IV: any level
DV: nominal/categorical (usually dichotomous/bimodal; 1=smokes 0=doesn’t smoke. Can have multinomial when DV has 3 or more categories)

Question 20

The odds of doing something(odds ratio) equals:

Answer 20

The probability of doing something divided by the probability of not doing it

Question 21

If there is a strong correlation between variables in a simple linear regression what does this mean?

Answer 21

This indicates a strong prediction of the outcome

Question 22

What does a logistic regression ultimately predict?

Answer 22

Categorical (nominal) DV

Question 23

Pearson’s r does not indicate causality and is not used in what type of study design?

Answer 23

Quasi-experimental

Experimental

Question 24

What test is used to compare the means of two or more groups while controlling for confounding variables?

Answer 24

ANCOVA (analysis of covariance)

Question 25

What levels or measurement are covariates used in an ANCOVA usually?

Answer 25

Interval/ratio level

Question 26

An ANCOVA may increase ______ validity when randomization is not possible.

Answer 26

Internal

ANCOVA may still be used in randomized experiments

Question 27

When is an ANCOVA applicable?

Answer 27

When researchers are using nonequivalent control group designs to test an intervention and researchers need to consider whether pre-existing group differences affected results. An ANCOVA can be used for post hoc stat testing

Question 28

What statistic does an ANCOVA result in?

Answer 28

F statistic

Question 29

What test is used to test the significance of differences in group means for multiple interval or ratio level DVs which are considered simultaneously?

Answer 29

MANOVA

Question 30

A MANOVA should be used instead of two or more separate ANOVA tests when there are multiple DVs to limit Type ____ error

Answer 30

I

Question 31

What statistic does a MANOVA result in?

Answer 31

F statistic

Question 32

Which multivariate statistical tests compare means and which predict outcomes?

Answer 32

Compare means: ANCOVA, MANOVA

Predict outcomes: simple linear, multiple, and logistic regression

Question 33

If the population multiple correlation coefficient is equal to 0, what does this represent?

Answer 33

The null hypothesis (there is no relationship between the variables)