Chapter 8: Hypothesis Testing

Question 1

hypothesis testing

Answer 1

A statistical method that uses sample data to evaluate a hypothesis about a population.

Question 2

goal of hypothesis testing

Answer 2

rule out chance (sampling error) as a plausible explanation for the results from a research study.

Question 3

4 steps of a hypothesis test

Answer 3

1. State hypothesis about the population
2. Use your hypothesis to predict the characteristics the sample should have.
3. Obtain a sample from the population
4. Compare data with the hypothesis prediction

Question 4

if individuals in the treated sample are different than the population there is _____ effect

Answer 4

evidence of an

Question 5

null hypothesis

Answer 5

states that there is no change in the general population before and after an intervention.
In the context of an experiment, the independent variable had no effect on the dependent variable

Question 6

alternative hypothesis

Answer 6

states that there is a change in the general population following an intervention.
In the context of an experiment, the independent variable did have an effect on the dependent variable

Question 7

null distribution

Answer 7

the distribution of the population if there is no effect of treatment

Question 8

what is the mean of a sample from the null distribution

Answer 8

same as the population mean

Question 9

if the sample is on the tails of the null distribution, then

Answer 9

there was an effect and we should reject the null hypothesis

Question 10

H₀

Answer 10

null hypothesis

Question 11

H1

Answer 11

alternative hypothesis

Question 12

α level

Answer 12

the criterion used to make a decision about the hypothesis

Question 13

common alpha levels

Answer 13

α = .01, α = .05 (most used), α = .001

Question 14

critical region

Answer 14

Outcomes that are very unlikely to occur if the null hypothesis is true.

Question 15

when do you decide on the alpha level?

Answer 15

before seeing the results

Question 16

non-directional hypothesis

Answer 16

doesn’t explicitly say if the treatment will increase or decrease the dependent variable

Question 17

z-values for an alpha level of 0.05

Answer 17

+ 1.96, -1.96

Question 18

z-values for an alpha level of 0.01

Answer 18

+2.58, -2.58

Question 19

z-values for an alpha level of 0.001

Answer 19

+3.30, -3.30

Question 20

rejecting the null hypothesis

Answer 20

treatment had an effect

Question 21

failing to reject the null hypothesis

Answer 21

treatment did not have an effect

Question 22

type 1 error

Answer 22

Occurs when the sample data appear to show a treatment effect when there is none. the researcher will reject the null hypothesis and falsely conclude that the treatment had an effect

Question 23

false positive is another word for a

Answer 23

type 1 error

Question 24

telling someone who’s not pregnant that they are is a

Answer 24

type 1 error

Question 25

type 2 error

Answer 25

Occurs when the sample does not appear to have been affected by the treatment when it does. In this case, the researcher will fail to reject the null hypothesis and falsely conclude that the treatment does not have an effect

Question 26

false negative is another word for a

Answer 26

type 2 error

Question 27

telling someone who’s pregnant that they are not is a

Answer 27

type 2 error

Question 28

type 1 errors are represented by

Answer 28

ɑ

Question 29

type 2 errors are represented by

Answer 29

β

Question 30

directional tests

Answer 30

include the directional prediction in the statement of the hypotheses and in the location of the critical region

Question 31

what type of hypothesis test is most common in psych research

Answer 31

nondirectional

Question 32

Two main differences between directional and non-directional hypothesis tests

Answer 32

• How you write and specify the null and alternative hypothesis
• The critical value associated with your cut-off
  5% cut-off with a two-sided test means 2.5 on either side corresponding to a z-score of 1.96 on either side
  5% cut-off with a one-sided test means 5.0 on one side, corresponding to a z-score of 1.65

Question 33

Raw effect size

Answer 33

the effect size in the original unit

Question 34

cohen’s d formula

Answer 34

d = M-μ/σ

Question 35

null distribution

Answer 35

distribution if there is no effect

Question 36

The probability of a type 1 error

Answer 36

Ɑ

Question 37

probability of a type 2 error

Answer 37

β

Question 38

power formula

Answer 38

1-β

Question 39

what is power?

Answer 39

Probability of detecting the effect if it exists

Question 40

what are typical values for power

Answer 40

0.8 or 0.9

Question 41

effect size and power

Answer 41

Larger differences between groups or sample and population will have more power

Question 42

sample size and power

Answer 42

Getting a bigger sample increases power, because it decreases the standard error

Question 43

a-value and power

Answer 43

Larger alpha values increase power

Question 44

directional vs. non-directional hypothesis tests and power

Answer 44

One tailed (directional) hypotheses have more power because the sample has to be less extreme for an effect to be found

Question 45

how can researchers influence power?

Answer 45

• choose a larger a-value
• get a larger sample size

Question 46

issue with hypothesis tests

Answer 46

they don’t indicate how large the effect is

Question 47

what cohen’s d value is associated with a small effect

Answer 47

0.2

Question 48

what cohen’s d value is associated with a medium effect

Answer 48

0.5

Question 49

what cohen’s d value is associated with a large effect

Answer 49

0.8