Chapter 7

Question 1

Z table

Answer 1

provides the percentage of scores between the mean and a given z value, which allows us to find its percentile rank and the percentage of scores at least as extreme as it (in both directions)

Question 2

Assumptions

Answer 2

characteristics we ideally require the population from which we are sampling to have so that we can make accurate inferences

Question 3

Parametric tests

Answer 3

inferential statistical analyses based on a set of assumptions about the population e.g. z test, t test, F test, Pearson’s r; more powerful

Question 4

Nonparametric tests

Answer 4

inferential statistical analyses that are not based on a set of assumptions about the population e.g. chi-square, spearman’s r

Question 5

3 main assumptions for parametric tests

Answer 5

(1) the dependent variable is assessed using a scale measure and IV is nominal (2) the participants are randomly selected (3) the distribution of the population of interest must be approximately normal (or as long as the sample size is at least 30 due to CLT)

Question 6

Robust hypothesis tests

Answer 6

those that produce fairly accurate results even when data suggests that the population might not meet some of the assumptions

Question 7

Critical values or cutoffs

Answer 7

test statistic values beyond which we reject the null hypothesis; usually one for extreme samples below the mean and one for those above the mean

Question 8

Critical region (i.e. rejection region)

Answer 8

area in the tails of the comparison distribution in which the null hypothesis can be rejected

Question 9

Alpha levels

Answer 9

probabilities used to determine the critical values

Question 10

P value

Answer 10

the probability of finding this particular test statistic, or one even larger, if the null hypothesis is true (no difference between means)

Question 11

Statistically significant

Answer 11

unlikely to get a result that is equally or more extreme by chance alone if the null hypothesis is true; does not necessarily mean the finding is important or meaningful

Question 12

2 possible sets of hypotheses

Answer 12

directional and nondirectional

Question 13

Directional hypothesis

Answer 13

predicting either an increase or a decrease, but not both

Question 14

Nondirectional hypothesis

Answer 14

predicting a difference in either direction

Question 15

One-tailed test

Answer 15

hypothesis test in which the research hypothesis is directional, positing either a mean decrease or a mean increase in the DV, but not both, as a result of the IV

Question 16

Two-tailed test

Answer 16

hypothesis test in which the research hypothesis does not indicate a direction of the mean difference or change in the DV, just that there is a mean difference

Question 17

HARKing

Answer 17

hypothesizing after the results are known

Question 18

2 main recommendations for reporting results

Answer 18

(1) distinguish clearly between the original hypothesis and those developed after seeing the results (2) report all variables, experimental conditions, and analyses

Question 19

P-hacking

Answer 19

the use of questionable research practices to increase the chances of achieving a statistically significant result

Question 20

When do we choose the z test?

Answer 20

when we have a sample that we are comparing to a population with a known mean and standard deviation