Exam 3

Question 1

scatterplot

Answer 1

graph of relationship between two variables, X and Y.

one point per subject

Question 2

correlation

Answer 2

Measure of how closely two variables are related
Population variable: p(rho)
Sample correlation variable : r

Question 3

Independence between two variables

Answer 3

value of one tells nothing about the other

Question 4

Linear Relationship

Answer 4

correlation measures how well data fit on a straight line

ie assumes linear relationship

Question 5

Regression

Answer 5

finds best combination of predictors to explain outcome variable

• determines unique contribution of each predictor
• -can test whether each predictor has reliable influence

Question 6

Regression equation

Answer 6

Yhat =

Question 7

Intercept

Answer 7

value of Y when all X’s are zero

Question 8

Regression coefficient

Answer 8

bi

• influence of Xi
• Sign tells direction; magnitude tells strength
• -can be any value (not standardized like correlation)

Question 9

Sum of squares

Answer 9

all of the squared deviations from the mean all added together

Question 10

Explained variability

Answer 10

the total sum of squares is the variability in Y therefore the explained variability

Question 11

residual variability

Answer 11

the deviation between predicted and actual scores

Question 12

F statistic

Answer 12

used for hypothesis testing

• -if F is larger than expected by H0, regression explains more variance than expected by chance
• • Reject null hypothesis if F is large enough

Question 13

Analysis of Variance (ANOVA)

Answer 13

single test for any group differences

• -Null Hypothesis: All means are equal
• -Works using variance of the sample means
• -Also based on separating explained and unexplained variance

Question 14

grand mean

Answer 14

the mean of sample means. You take all the means add them together and divide them by how many subjects there are

Question 15

Repeated-Measures Design

Answer 15

Multiple measurement for each subject

• -different stimulus types, conditions, times, etc
• -All measurements are of the same variable, but in different situations
• -Generalizes paired-samples design

Question 16

individual differences

Answer 16

• -variation from one subject to another

- -affects all scores of any given subject

Question 17

Hypothesis test for repeated-measures ANOVA

Answer 17

F = MS treatment/ MS residual

Question 18

Repeated-Measures ANOVA

Answer 18

Same as regular ANOVA, except we first remove SS subject

–SS subject not meaningful with simple ANOVA because each subject is in one group

Question 19

Factor

Answer 19

In the context of analysis of variance an independent variable or quasi-independent variable is called a factor

Question 20

Factorial ANOVA

Answer 20

Extends ANOVA in the same way regression extends correlation

–explains how each factor affects the outcome

Question 21

main effect

Answer 21

tests the effects of each factor on the outcome