Module 9: Inferential Statistics

Question 1

Why do researchers use inferential statistics?

Answer 1

To determine cause and effect
Compare differences between groups
To determine relationships amount variables
Estimate a population parameter

Question 2

Statistical inference consists of what 2 techniques

Answer 2

Estimation of parameters

Hypothesis testing

Question 3

What is point estimation?

Answer 3

The computation of a value (by the computer) that will estimate your population parameter

Question 4

Why do researchers do an interval estimation instead of point estimation?

Answer 4

D/t the margin of error associated with using one point like in point estimation. Interval estimation uses a range of values around which the population parameter will lie

Question 5

What is the terms used to describe the range of values within which a population parameter is estimated to lie?

Answer 5

Confidence interval (95%)

Question 6

What does the statement:95% of scores lie within 2 SD of the mean? (CI)

Answer 6

We’re 95% confident that the correct value for our population mean (mu) lies within that range of scores

Question 7

Hypothesis testing uses _______ criteria for deciding whether a hypothesis is supported by data.

Answer 7

objective

Question 8

What is a major factor influencing standard error of the mean?

Answer 8

Sample size

Question 9

What does hypothesis testing help to distinguish?

Answer 9

Whether differences in the population occurred by chance or were true population differences

Question 10

What type of tailed test is typically used if a researcher has stated a directional hypothesis?

Answer 10

One tailed 
(nondirectional= two tailed, many will run two tailed just ot be sure with a directional)

Question 11

What does the null hypothesis state?

Answer 11

That there is NO relationship between variables

Question 12

Describe alpha related to level of significance. (value, who set by, probability of ____)

Answer 12

0.05, 5% of the time results occurred by chance
Set by researcher
Probability of making a Type I error

Question 13

Describe statistical significance, p value. (value, set by, allow us to ____)

Answer 13

<0.05= statistical sig (less than 5% of the time the results occured by chance)
>0.05= not statistical sig (over 5% of the time the results did occur by chance)
Set by/calculated by computer
Allows us to know if we can accept or reject the null

Question 14

Which statistical tests are higher level and more powerful?

Answer 14

Parametric

Question 15

In parametric statistical testing what level of measure of data is the DV and the IV?

Answer 15

IV: nominal (ex-gender, ethnic groups)
DV: interval

Question 16

In parametric statistical testing we assume that data is _______ distributed.

Answer 16

normally

normality assumption

Question 17

Parametric statistical tests allow researchers to compare _____ ______ .

Answer 17

group means

Paired t-test, independent t-test, ANOVA

Question 18

Parametric statistical tests also allow researchers to determine ________ among two variables, at _____ level.

Answer 18

relationship
interval
(Pearson’s r- correlation)

Question 19

In nonparametric statistical testing what level of measurement are the DV and IV?

Answer 19

IV: nominal
DV: non-interval level

Question 20

What do we assume about nonparametric statistical testing in relation to the normality assumption?

Answer 20

We assume they do NOT meet the normality assumption (data is skewed)

Question 21

Nonparametric statistical testing can compare group means and relationships between two variables at _________ level

Answer 21

non-interval level
Comparing groups: Chi Square, Mann-Whitney U, Kruskal-Wallis
Relationship: Phi coefficient, Spearman’s rho

Question 22

Which parametric procedure is used for testing differences in group means?

Answer 22

t-tests

Question 23

When is a Bonferroni correction applied by researchers?

Answer 23

When running multiple tests with the same data to establish a more conservative alpha and avoid a Type I error (this correction runs the risk of creating a Type II error by decreasing alpha to 0.017 for example)

Question 24

Parametric:

When means for two sets of scores are dependent, researchers use a _____ _ _____. Often a pretest/posttest design.

Answer 24

Paired t-test

Question 25

Parametric:

When means for two sets of scores are independent, researchers use an _____ _ _____. Measured one time only

Answer 25

Student’s (Independent) t-test

Question 26

Non-parametric:
In an independent two-group situation where the dependent variable is non-interval level or the distribution is markedly non-normal, what test is used?

Answer 26

Mann-Whitney U test

Question 27

Non-parametric:

When non-interval level data are paired (dependent) and measured two times which test is used?

Answer 27

Wilcoxon signed ranks test

involves taking the difference between paired scores and ranking the absolute difference

Question 28

Which parametric test is used to test differences between means when there are three or more groups?

Answer 28

ANOVA

Question 29

What statistic is computed using an ANOVA?

Answer 29

F-ratio

Question 30

What nonparametric test is similar to the Mann Whitney U in that it is based on assigning ranks to the scores of various groups but is comparing greater than two groups and a one-way test for independent samples is desired?

Answer 30

Kruskal-Wallis

Question 31

What nonparametric test is used for more than two dependent groups where data is measured by repeated measures?

Answer 31

Friedman Test

Question 32

Which test is used to test hypotheses about group differences in proportions?

Answer 32

Chi-square test

computed using observed frequencies and expected frequencies

Question 33

What are the indices that describes correlational relationship between two nominal level, ordinal level, and interval level dichotomous variables?

Answer 33

Nominal: Phi coefficient
Ordinal: Spearman’s Rho
Interval: Pearson’s-r