T-Tests

Question 1

What are the 2 types of T-tests?

Answer 1

Unpaired / independent/ unrelated samples t-tests
Paired / dependent / related samples t-tests

Question 2

Are t-tests parametric or non-parametric?

Answer 2

Parametric tests
used when data is interval or ratio

Question 3

When receiving results from a t-test, what do you look at?

Answer 3

how far apart means are from each other
in the context of the variance of the data

Question 4

Is there a significant difference if there’s a small mean difference but a large difference?

Answer 4

unlikely to have a significant difference

Question 5

What is the t-test used for a between subjects design?

Answer 5

Unpaired / independent / unrelated samples t-test
comparing 2 different groups

Question 6

Who created the independent samples t-test?

Answer 6

William Gosset

Question 7

What is the independent samples t-test assumptions?

Answer 7

• data must be continuous (interval or ratio)
• normally distributed data
• data must have homogeneity of variance

Question 8

How do we know if we have homogeneity of variance (HoV)?

Answer 8

using the Levene’s test

Question 9

If the Levene’s test is non-significant (p-value above 0.05), what does that mean for HoV?

Answer 9

means we have homogeneity of variance

Question 10

If Levene’s test is significant, what does that mean for HoV?

Answer 10

means homogeneity of variance is not found and violated

Question 11

What is the Levene’s test?

Answer 11

tests the null hypothesis that the population variances are equal
increases our likelihood of finding a type 1 error (false positive)

Question 12

What are effect sizes and what is one example of one?

Answer 12

effect sizes are how big the difference between the two groups mean are
example = Cohen’s d

Question 13

How are effect sizes interpreted?

Answer 13

small = 0.2
medium = 0.5
large = 0.8

Question 14

What are confidence intervals?

Answer 14

intervals which are expected to contain the parameter being estimated
give 95% CIs as a rule

Question 15

What kind of estimate does a narrow confidence interval give?

Answer 15

precise estimate

Question 16

What kind of estimate does a wide confidence interval give?

Answer 16

imprecise estimate

Question 17

What is a Welch test?

Answer 17

an alternative to the independent samples t-test
does not assume homogeneity of variance
df in a welch test always has decimals

Question 18

What t-test is used for a within subject design?

Answer 18

Paired / dependent / related samples t-test
used when comparing one group at 2 diff times or conditions

Question 19

What is the dependent samples t-test assumptions?

Answer 19

• data must be continuous (interval /ratio)
• normally distributed