Stats help Mult

Question

1)In a t test for dependent means, 15 participants are each tested twice. This makes a total of 15 "before" scores and 15 "after" scores. What are the degrees of freedom?

a. 15

b. 14

c. 30

d. 29

2)When conducting an experiment with 95% power, failing to reject the null hypothesis means that

a. there is no difference between the experimental and control populations.
b. the experiment was poorly conducted.

c. the null hypothesis is true.

d. the chance that the data came from populations with a difference larger than that predicted when calculating power is less than 5%.

3)A psychologist conducts a study and finds that d = 1.41. This effect size would most likely be described as

a. small

b. medium

c. large

d. an error because d cannot be greater than 1

 

 

 

Answer 1

Theresa:

 

1)In a t test for dependent means, 15 participants are each tested twice. This makes a total of 15 "before" scores and 15 "after" scores. What are the degrees of freedom?

b. 14

The test is based on differences of values in each pair.  There are fifteen of them.  Hence the DF are 14.

 

2)When conducting an experiment with 95% power, failing to reject the null hypothesis means that

d. the chance that the data came from populations with a difference larger than that predicted when calculating power is less than 5%.

 

Power is the chance of rejecting the null hypothesis when it is false. However, answer (d) is not clearly worded.  I would choose that the "closest possible answer".

 

3)A psychologist conducts a study and finds that d = 1.41. This effect size would most likely be described as
a. small
b. medium
c. large
d. an error because d cannot be greater than 1

 

The answer depends on how d is defined.  Is d standardized?  Is it the sample mean of the differences between paired scores?  Is it "Ψ"?  And so on.

 

Dr. G.

Answer 2

This seems like a test!! We can't give answers to the test we can show you how to solve the stats problem. Stats can be difficult. Giving you the answer isn't helping you.