Null Hypothesis/Significance Testing

Question 1

Define inferential stats

Answer 1

Tell us if the IV is affecting the DV

Question 2

What is the purpose of stats in psychology?

Answer 2

see if data supports hypothesis
Make conclusions based on empiricism
make inferences about reasoning behind things

Question 3

What is variability?

Answer 3

the less overlap between groups, the more they differ

Question 4

What is a key point when selecting sample size?

Answer 4

the bigger, the less error in estimating the population

Question 5

Relying solely on _________ without sample size is a big mistake.

Answer 5

variability

Question 6

We use statistics to confirm if observed group differences from a sample are likely to reflect what?

Answer 6

True differences in the population

Question 7

We have found support for our hypothesis when…?

Answer 7

When the differences in the comparing groups are sufficient enough that it is unlikely that they happened by chance.

Question 8

What is the probability theory used to determine?

Answer 8

The likelihood that there is no true difference in pop. based upon what we used in sample.

Question 9

What is the null hypothesis?

Answer 9

Says the IV had no effect on the DV

There is no difference between groups and no association btw variables

Question 10

What does the alternative hypothesis say?

Answer 10

The opposite of the null

Question 11

If we reject the null, what does it mean?

Answer 11

There is a true difference

Question 12

If we fail to reject the null, what does that mean?

Answer 12

It’s unlikely that there is a true difference

Question 13

What are some limits of NHST?

Answer 13

Cannot prove causality

Cannot say anything about magnitude of an effect, only that there is an effect.

Question 14

What is the p-value?

Answer 14

The probability of getting the observed effect if the null was true (probability that result occurred by chance)

Question 15

What is the alpha level?

Answer 15

the p value threshold that needs to be crossed in order to reach statistical significance

Question 16

For the alpha level, probability should be less than how much?

Answer 16

5 % chance that the observed effect would occur if there were no real effect in the population

Question 17

In general, the _______ the p value the greater the chance the effect is “real” and will be replicated in another study.

Answer 17

smaller

Question 18

What can you expect if you set your p at .01 instead of the usual .05?

Answer 18

the more analyses you do, the greater likelihood of catching something significant, even if it’s not a true effect

Question 19

Alpha level is the threshold p needs to be under to ________ the null hypothesis

Answer 19

reject

Question 20

P

Answer 20

Reject null, accept alternative hypothesis

Question 21

P > .05?

Answer 21

Fail to reject null, can’t support the alternative hypothesis

Question 22

If the difference between groups is likely to be a true difference?

Answer 22

Compare and evaluate group means and SD

Question 23

if the association between variables is like to be a true association

Answer 23

Compare and evaluate correlations

Question 24

We are testing the probability that ______ is true.

Answer 24

null hypothesis

Question 25

Give an example of the test of probability for the null

Answer 25

Probability of finding the difference in our sample if, at the true population level, there is no difference between estimated and actual calories consumed

Question 26

Define p

Answer 26

Probability less than 5% that the observed effect would occur if there were no real effect in the population.

Question 27

The _________ the probability, the greater the chance that the effect is real and will be replicated in another study.

Answer 27

smaller

Question 28

If p

Answer 28

reject

Question 29

if > .05 you must __________ the null.

Answer 29

fail to reject the null

Question 30

What most common type of error occurs from running many analyses?

Answer 30

Type 1 error