RESEARCH STATISTICAL TESTS

Question 1

Aka two-sample t-test. It is a statistical test that determines if there is a significant difference between the means of two independent or unpaired groups. Its variable is continuous.

Answer 1

Independent Samples T-Test

Question 2

Groups in which cases or participants in each group are different.

Answer 2

Unpaired/unrelated groups

Question 3

Requirement and Assumption for Independent Samples T-Test

Answer 3

1. Random sample data from population
   2 Two groups are unrelated
2. Dependent variable must be continuous and normally distributed in each group
3. No significant outliers
4. Variance of dependent variable across groups should be equal. (Homegeneity of variance)

Question 4

Methods in Checking Outliers

Answer 4

1. IQR Method

2. Boxplot

Question 5

IQR Formula

Answer 5

Q3-Q1

Question 6

Lower-bound formula

Answer 6

Q1-(1.5 x IQR)

Question 7

Upper-bound formula

Answer 7

Q3+(1.5 x IQR)

Question 8

True or False. Any points lesser than lower bound and higher than upper bound are outliers.

Answer 8

True

Question 9

True or False. If outliers exist, we must leave them in.

Answer 9

False. Delete the outliers.

Question 10

Methods for Checking Normality

Answer 10

1. Distribution Plots
2. Q-Q Plots
3. Shapiro-Wilk test

Question 11

True or False. For Q-Q Plots, if all points are close to the diagonal reference line, then it is normally distributed.

Answer 11

True

Question 12

For Q-Q Plots, if points sag above or below the diagonal reference line, then there is a problem with the ________.

Answer 12

kurtosis

Question 13

If points snake around the diagonal reference line, then there is a problem with the ________.

Answer 13

skewness

Question 14

It is used to test null hypothesis that variances in different groups are not equal.

Answer 14

Levene’s Test

Question 15

In Levene’s Test, the variances are heterogenous if ________.

Answer 15

p-value is less than or equal to alpha

Question 16

In Levene’s Test, the variances are homogenous if ________.

Answer 16

p-value is more than alpha

Question 17

In Levene’s Test, if variances are heterogenous then we ________.

Answer 17

Reject the null hypothesis

Question 18

In Levene’s Test, if variances are homogenous then we ________.

Answer 18

Fail to reject null hypothesis

Question 19

Used to compare differences between two independent groups when the dependent variable is ordinal or numeric, but not normally distributed.

Answer 19

Mann-Whitney U Test

Question 20

Assumptions of Mann-Whitney U Test

Answer 20

1. Two groups should be independent

2. Dependent variable must be numeric or ordinal and is not normally distributed

Question 21

This test is used to compare means that are from the same related units. The 2 groups typically represent 2 different times. It aims to determine whether or not the mean difference between paired observations is significantly different from zero.

Answer 21

Paired Samples T-Test

Question 22

Assumptions of Paired Samples T-Test

Answer 22

1. Random sample data from population
2. Two groups should be dependent or paired
3. Dependent variable must be continuous.
4. No outliers in either of the 2 groups.
5. The difference of observations of the paired groups should be normally distributed.

Question 23

In Paired Samples T-Test, “the difference between group 1 and 2 is equal to zero” represents the ________.

Answer 23

null hypothesis

Question 24

In Paired Samples T-Test, “the difference between group 1 and 2 is NOT equal to zero” represents the ________.

Answer 24

alternative hypothesis

Question 25

This is the nonparametric alternative test for the Paired Samples T-test. It is used to compare 2 sets of variables that are of either ordinal level of measurement or numeric that are from paired observations, usually, from the same participants.

Answer 25

Wilcoxon Signed Rank Test

Question 26

Assumptions of Wilcoxon Signed Rank Test

Answer 26

1. Two groups should be dependent or paired

2. Dependent variable must be numeric or ordinal

Question 27

Used to compare the means of 2 or more independent groups in order to determine whether there is a statistical evidence that the associated population means are significantly different.

Answer 27

Analysis of Variances (ANOVA)

Question 28

Requirements and Assumptions of Analysis of Variances (ANOVA)

Answer 28

1. Independent variable should be categorical.
2. Dependent variable must be numeric and normally distributed.
3. The variances of the dependent variable across groups should be equal. (Homogeneity of Variances)

Question 29

Used if in ANOVA, the null hypothesis is rejected.

Answer 29

Post-Hoc Tests

Question 30

Three common Post-Hoc Tests:

Answer 30

1. Least Significant Difference (LSD)
2. Tukey’s Honestly Significant Difference (HSD) Test
3. Scheffe’s Test

Question 31

Used to compare the means of 2 or more independent groups in order to determine whether there is a statistical evidence that the associated population means are significantly different. And if normality is not satisfied.

Answer 31

Kruskal-Wallis Test

Question 32

If the test assumes normality then it is _______.

Answer 32

Parametric

Question 33

If the test do not assume normality then it is _______.

Answer 33

Nonparametric

Question 34

This Post-Hoc test is good for exactly 3 groups.

Answer 34

Least Significant Difference (LSD)

Question 35

A Post-Hoc test that is good when Homogeneity of Variances is satisfied.

Answer 35

Tukey’s Honestly Significant Difference (HSD) Test

Question 36

This Post-Hoc test is good when sample sizes are different.

Answer 36

Scheffe’s Test