Module 2: Elementary Arguments & the Role of Chance

Question 1

Researchers typically aim for a power criteria of…

Answer 1

.80 (80%)

Question 2

Type I error

Answer 2

Concluding a mean difference exists in the populations (rejecting the null) where there is no difference (the null is true)
ALPHA

Question 3

What are the statistical assumptions for an independent samples t-test (there are 3)

Answer 3

1. Groups are independent of each other
2. Sample means are normally distributed
3. Homogeneity of variance between groups

Question 4

p value > 0.05 =

Answer 4

Fail to reject the null hypothesis

Question 5

p value < 0.05 =

Answer 5

Discredit the null hypothesis

Question 6

The smaller the p-value the more ________ variation there is

Answer 6

systematic

Question 7

Type II error

Answer 7

Concluding NO mean difference exists in the population (failing to reject the null) when there is in fact a difference in means (the null is false)
BETA

Question 8

What is power’s relation to type II error?

Answer 8

Power is inversely related to type II error (if one increases the other decreases and vice versa)

Question 9

The stricter the alpha, the lower the _______

Answer 9

power

Question 10

Power

Answer 10

likelihood of a test finding an existing effect

Question 11

The larger the sample size, the greater the ______

Answer 11

power

Question 12

The larger the effect of the independent variable, the greater the _______

Answer 12

power

Question 13

Determinants of power (there are 3)

Answer 13

1. Alpha
2. Sample size
3. Effect size

Question 14

What is the null hypothesis of an independent samples t-test?

Answer 14

The sample means of the populations are the same

Question 15

What is the null hypothesis of the repeated (paired) samples t-test?

Answer 15

The sample means of each condition are the same

Question 16

What is a disadvantage of the repeated measures t-test?

Answer 16

Mustcontrol fororder effects through counterbalancing

Question 17

What isa disadvantageof the independent samples t-test?

Answer 17

Requires a larger sample sizeto achieve an acceptable level of power

Question 18

What is an advantage of the repeated measures t-test?

Answer 18

Requires fewer participants AND has more power

Question 19

What is an advantage of the independent samples t-test?

Answer 19

Do not have tocontrol fororder effects AND participants are less susceptible to demand characteristics

Question 20

Standard error

Answer 20

The variability across means of multiple samples in a population; the standard deviation of sample means

Question 21

The smaller the standard error…

Answer 21

The less variation that will exist within a sample

Question 22

What are the statistical assumptions for a repeated measures t-test (there are 2)

Answer 22

1. Groups are independent of each other

2. Sample means are normally distributed