Brown: Chapter 5

Question 1

When is inferential statistics used?

Answer 1

Inferential statistics is used when a researcher wants to infer, or conclude/suggest from evidence and reasoning, something about a larger population based on a sample used in a study.

Question 2

Parametric statistics assume…

Answer 2

the distribution of scores in the sample are normally distributed

*nonparametric stats are distribution free

Question 3

What is statistical significance?

Answer 3

a number that expresses the probability that the result of a given experiment or study could have occurred purely by chance
Statistical significance is reported as a p value.
Probability is how likely something is to happen.

Question 4

What is level of significance?

Answer 4

a
the amount of risk you are willing to assume when conducting a study
Most researchers use 0.05.
This means a 5% risk that the difference between two groups is not a true difference, but instead occurred by chance (and a 95% chance that it is a true difference).

Question 5

What is a t-test?

Answer 5

the most basic of inferential difference statistics because it examines the difference between two groups at a single point in time, or one group at two time points

Question 6

What is a t-test for independent samples?

Answer 6

also known as a two-group/two-sample t-test or an unpaired sample t-test
compares the difference in the mean score for two unrelated groups (between-group comparison)

Question 7

What is a t-test for dependent samples?

Answer 7

also referred to as a paired-sample t-test
compares the pretest and posttest scores of a single group (within group comparison).

Question 8

What is an ANOVA?

Answer 8

the test for comparing more than two means

Question 9

What is a one way ANOVA?

Answer 9

(similar to the between-group t-test) compares three or more groups on a single dependent measure

four groups, one time point

Question 10

What is a repeated measures ANOVA?

Answer 10

(similar the within- group t-test) is used when the means are compared over three or more time points

one group, four time points

Question 11

What is a mixed model ANOVA?

Answer 11

used when between- and within-group analyses are conducted simultaneously (two or more groups are compared over two or more time points)

Question 12

What is this graph showing?

Answer 12

no main effect for time or group and no interaction effect

Question 13

What is this graph showing?

Answer 13

a main effect for time, but no main effect for group and no interaction effect

Question 14

What is this graph showing?

Answer 14

a main effect for time and a main effect for group, but no interaction effect

Question 15

What is this graph showing?

Answer 15

an interaction effect

Question 16

What is an ANCOVA?

Answer 16

Analysis of covariance
Used when a researcher wants to statistically control a variable that could affect the outcome of a study

Question 17

When are nonparametric statistics used?

Answer 17

When the assumptions for parametric statistics are not met
The data is not normally distributed (this requires a sample size of 30 or more participants)

Question 18

What is a chi square?

Answer 18

The chi square determines if there is a statistically significant difference between frequencies in two or more groups

Question 19

What is a Mann-Whitney test?

Answer 19

The Mann-Whitney test compares two groups and is used when the parametric assumptions are not met (comparable to the independent sample t-test)

Question 20

What is a Kruskal Wallis test?

Answer 20

The Kruskal Wallis test is similar to the Mann-Whitney test, but it is used when three or more groups are compared (nonparametric equivalent of the one-way ANOVA)

Question 21

What does the effect size describe?

Answer 21

the magnitude or strength of a statistic

Question 22

What is a confidence interval?

Answer 22

a reliability estimate that suggests the range of outcomes expected for the population

Question 23

What information does power provide?

Answer 23

Power provides information about the likelihood of detecting a difference if it exists.

Question 24

What does Cohen’s d measure?

Answer 24

the difference between two group means reported in standard deviation units