Lecture 14

Question 1

Lecture 14:

What does ANOVA stand for?

Answer 1

Analysis of Variance

Question 2

Lecture 14:

When would you use an ANOVA test?

Answer 2

Used when more than two group means are being tested at the same time (simultaneously)
- participants only tested once & only one dependent variable

Question 3

Lecture 14:

What is the Test Statistic for an ANOVA test?

Answer 3

Test statistic = F-test which compares means and adjusts fir uneven group sizes

Question 4

Lecture 14:

What is a One-Way ANOVA?

Answer 4

A one-way analysis of variance used when one factor or one treatment variable has more than two levels

Question 5

Lectrue 14:

What is an example of a One-Way ANOVA?

Answer 5

Measuring math scores of 3 different age groups:

IV = math skill & levels of IV = high, moderate, & low
DV = performance

Question 6

Lecture 14:

Why do you have to do a One-Way ANOVA instead of 3 t-tests?

Answer 6

Multiple t-tests on the same dat increases the Type I error rate (increases odds of rejecting null hypothesis when actually true)
- multiple t-tests would only consider variance for 2 samples, ignoring the variance for 3rd sample

Question 7

Lecture 14:

What are the Variance between groups?

Answer 7

The gap between two variances & the effect we are interested in
*want the between-group variance to be large & within-group variance to be small

Question 8

Lecture 14:

What are within group variances?

Answer 8

Variance within the variable & the error between members of each group

*want the between-group variance to be large & within-group variance to be small

Question 9

Lecture 14:

What are 4 Assumptions/Requirements for ANOVA test?

Answer 9

1.) Continuos measurement
2.) scores for each group = independent
3.) data = normally distributed
4.) homogeneity of variance

Question 10

Lecture 14:

What is the first step to Conducting an ANOVA test?

Answer 10

State your hypothesis (null & research)
- ANOVA does not allow a one-tailed or two-tailed test & does not look at which groups/comparisons are difference (pairwise differences)
- Post Hoc tests required

Question 11

Lecture 14:

What is a Post hoc test?

Answer 11

An additional test that specifically identifies which group is different from which other group

Question 12

Lecture 14:

What is the second step to conducting an ANOVA test?

Answer 12

Set the level of risk associated with the null hypothesis (alpha) Eg; a = 0.05

Question 13

Lecture 14:

What is the third step to conducting an ANOVA test?

Answer 13

Selecting the appropriate test statistic & test assumptions (one-way simple ANOVA)

Question 14

Lecture 14:

What is the fourth & Fifth step to conducting an ANOVA test?

Answer 14

Computing the F statistic

Question 15

Lectrue 14:

What is the formula for the F statistic?

Answer 15

F = MS between/ MS within

MS between = mean square between groups
MS within = mean square within groups

*hoping variance is larger in within than between

Question 16

Lecture 14:

How do you find/calculate MS between?
- 4 steps

Answer 16

MS between = SS between / df
*df = K - 1 —> K = # of groups
1.) diff b/with each group mean & overall mean
2.) square each difference
3.) multiply each result by the N in each group
4.) add values for each group together

Question 17

Lecture 14:

How do you calculate MS within?
- 3 steps

Answer 17

MS within = SS within / df within

1.) find difference b/w each individual’s score & their group mean
2.) square each difference
3.) add all values together

Question 18

Lecture 14:

What is the Numerator df?

Answer 18

The number of groups (k) minus one
Eg; 3 groups —> df = 3-1 = 2

Question 19

Lecture 14:

What is the Denominator df?

Answer 19

The total number of observations minus the number of groups
Eg; 18 participants —> df = 18-3 = 15

Question 20

Lecture 14:

How do you interpret an ANOVA?

Answer 20

Compare the F statistical to the F critical & compare it to the alpha value