4. Muligroup: Independent Groups

Question 1

Why use ANOVAs?

Answer 1

Multiple t-test ➡️ increased risk of type 1 errors

14.3% for a 3 t-test comparison

Question 2

When would we use the one-way (independent) ANOVA?

Answer 2

When we are looking at 1 variable (e.g. social support) in different IVs (e.g. marital status).

Question 3

What does the one-way ANOVA test do?

Answer 3

It compares the variance between groups (assumed to be due to the IV) to the variance in each group (due to chance).

Question 4

What is the F-ratio?

What does a large F ratio mean?

Answer 4

Variance btwn groups
➗
Variance within groups

Large = more variability between groups (caused by IV)

Question 5

What’s an alt test to the F-test to perform on the one-way ANOVA?

What does a NON significant result mean?

Answer 5

Homogeneity of variance test, brown-forsythe and Welch).

If test is non-significant, then the groups are similar. The ANOVA can therefore be trusted.

Question 6

How would we report the one way ANOVA?

Answer 6

🔸F (anova test)
🔸p value
🔸d.f.

F(df1, df2…) = ❔, p = ❔

Question 7

If the levene statistic is significant, what do we look at?

Answer 7

Welch or Brown-Forsythe and report adjusted F-ratio

Question 8

What doesnt the ANOVA tell us?

Answer 8

Where the difference lies [in variance].

Need to do more tests:
🔸planned or post hoc tests

Question 9

What are post- hoc tests led by? Name some post-hoc tests.

What are planned comparisons led by?

Answer 9

🔸are data led; didnt plan to look at data until it showed a difference

🔹tukey
🔹scheffe

🔸pllanned comparisons led by theory

Question 10

Effect size ANOVAS:
🔸rather than cohen’s d, what is reported?
🔸hows it calculated?
🔸boundaries?

Answer 10

🔸partial eta squared (np^2)

sum of squares btwn groups ➗ total sum of squares

🔸small ➖ 0.01
🔸medium ➖ 0.06
🔸large ➖ 0.14

Question 11

Kruskal- Wallis
🔸what is it?
🔸what is its output?

Answer 11

🔸 non para equivalent of one way independent ANOVA.
🔸is similar to Mann Whitney U

🔸 X^2 is output