ANOVA & Paired t-Test Exam 2

Question 1

When would you use Independent groups t-test?

Answer 1

xContinuous variable compared across two discrete independent groups that are part of one variable

Question 2

When would you use Analysis of variance (ANOVA)?

Answer 2

Continuous variable compared across three or more discrete independent groups that are part of one variable

Question 3

When would you use Dependent groups (paired) t-test?

Answer 3

Continuous variable compared across matched measurements in two discrete dependent groups that are part of one variable

Question 4

What are the assumptions that must be met for ANOVA?

Answer 4

• samples are random
• a person is only in one group (independent samples)
• there are independent observations within groups (one observation per person)
• data is normally distributed,
• variances are similar to one another

Question 5

What are the assumptions that must be met for Dependent groups (paired) t-test?

Answer 5

• one group is measured twice (ex. baseline and post-treatment)
• there may be a correlation between those two values

Question 6

t-statistic value

Answer 6

• As difference between the means increase, the value of t increases
• As variability increases (in the denominator; aka the more dispersion), the value of t decreases,
• as sample size increases, the value of t increases,
• as the correlation increases, the value of t increases

Question 7

What is the F test?

Answer 7

measures if there is a difference between the group means

Question 8

What is the null hypothesis for the F test?

Answer 8

there is no difference among group means

Question 9

In a F-test, what is the degrees of freedom?

Answer 9

N-1

Question 10

What is is n^2?

Answer 10

tells you what percentage of the variance that we see is explained by our one grouping variable

Question 11

Planned comparison technique used in ANOVA

Answer 11

• Hypotheses specified before the analysis commences

* Typically involve all possible comparisons

Question 12

Post-hoc comparison technique used in ANOVA

Answer 12

• Performed after some significant difference has been found via F test
• Tukey’s HSD (honest significance difference) test corrects for inflated alpha
• Further exploration of data after a significant effect has been found
• Typically involve two comparisons at a time