week 6

Question 1

Analysis of variance

Answer 1

parametric test
Compares mean scores across conditions
2+ conditions

Question 2

Factor

Answer 2

The independent variable.

In a study of the effect of type of drink on reaction time, type of drink would be the FACTOR.

Question 3

Level

Answer 3

The separate conditions present within the factor.

If we include caffeinated coffee, decaf and water as three types of drink we can give our participants, then our factor: drink type would have THREE LEVELS.

Question 4

One-way ANOVA

Answer 4

An ANOVA with only one factor consisting of any number of levels (for example, two, three, etc) . Each level will require an independent sample- meaning: each level needs a different group of participants;

Question 5

ANOVA Assumptions

Answer 5

Homogeneity of variance (i.e., the distribution, or “spread,” of scores around the mean of your samples are equal).

Normally distributed data

Yourdependent variableshould be continuous. E.g. revision time (measured in hours), intelligence (measured using IQ score), exam performance (measured from 0 to 100), weight (measured in kg)

Yourindependent variableshould consist ofthree or more categorical,independent groups. E.g. ethnicity, physical activity level, profession

Question 6

Two-Way ANOVA

Answer 6

An ANOVA in which there are 2 or more factors

The main effect of IV 1 (Factor 1)
Is there a difference in the dependent variable between the conditions in IV 1
The main effect of IV 2 (Factor 2)
Is there a difference in the dependent variable between the conditions in IV 2
The interaction between IV 1 and IV 2
Is there a difference in the dependent variable based on the combination of conditions in IV 1 and IV 2
Does the effect of one IV change depending on the level of the other IV?

Question 7

Steps in Calculating a Two-way Within-subjects ANOVA

Answer 7

Calculate the descriptive statistics
Means and SD

Calculate and interpret the ANOVA
The two main effects
Sphericity
The interaction

Post-hoc tests

Question 8

Additional Assumptions

Answer 8

Mauchly’s test
if significant: sphericity assumption violated- we will need to read different lines of the SPSS output depending on whether the test is significant or not