Biostat Chapter 12-13

Question 1

ANOVA

Answer 1

one-way analysis of variance

one-way because 1 explanatory variable is considered

It is “analysis of variance” because variation in the response is analyzed as a way of gaining insight into group differences.

Question 2

ANOVA works by dividing variance in a data set into these two components:

Answer 2

“Variance Between Groups” aka “Mean Square Between”

“Variance within Groups” aka “Mean Square Within”

Question 3

Mean Square Between (MSB)

Answer 3

quantifies the variance of group means around the grand mean. This is an estimate of “Variance Between Groups”

Question 4

Mean Square Within (MSW)

Answer 4

quantifies the variability of data points in a group around its mean. This is the estimate of the “Variance Within Groups”

Question 5

F-statistic

Answer 5

the ratio of the MSB and MSW. A large Fstat suggests that the observed mean differences are not merely due to random noise

Fstat = MSB
————
MSW

Question 6

Single Samples

Answer 6

reflect the experience of a single group. No concurrent control group is present, but results may be compared to previously established norms or expected values.

Question 7

Paired Samples

Answer 7

use data from two samples. each data point in the first sample is uniquely matched to a data point in the second sample.

Question 8

Independent Samples

Answer 8

data points in two samples are unrelated