Quiz 10

Question 1

What are the parametric assumptions?

Answer 1

1. independent, unbiased samples
2. data normally distributed
3. equal variances

Question 2

How does the Shapiro test tell us about the distribution of data?

Answer 2

if p value of shapiro test is below 0.05, it is not normally distributed
If 0.05 or above, then it is normally distributed

Question 3

Listen to audio around 4 min Nov 22

Question 4

What does df stand for in R? (not data frame)

Answer 4

degrees of freedom

Question 5

LISTEN TO AUDIO for how to report values (around 9 min)

Answer 5

don’t report 2.2e-16
listen for how to report p-values
(9 min audio)

Question 6

What is a 2-tailed test?

Answer 6

• you have 2 possibilities that align with your decision (you say 2 means are different without saying which one is higher or lower—so you have 2 possibilities: group A is higher than B, or group B is higher than A)

Question 7

What is a 2-tailed hypothesis?

Answer 7

One that doesn’t specify which of 2 possibilities is true
So a 1-tailed (null) hypothesis would state a specific possibility ex. “The mean of the stressed group is not greater than the mean of the unstressed group”

Question 8

easier to find significant p-value if running a 1-tailed test

Answer 8

BUT, if you ran a 2-tailed test and didn’t get significant p-value, shouldn’t switch to 1-tailed in order to try to find significance (“p-hacking”)

Question 9

look in zip file in documents, file name t_test_unpaired for instructions and scripts from today