Research Methods Y2 - Choosing a Statistical Test

Question 1

What are the three factors to consider when choosing a statistical test?

Answer 1

1. Whether the researcher is looking for a difference or correlation. 2. The experimental design being used. 3. The level of measurement.

Question 2

What is the Chi-Squared test used for?

Answer 2

A test for an association, difference, or correlation between two variables or conditions. Data should be nominal level using an unrelated (independent) design.

Question 3

What is the Mann-Whitney test used for?

Answer 3

A test for a significant difference between two sets of scores. Data should be at least ordinal level using an unrelated (independent) design.

Question 4

What is Pearson’s r used for?

Answer 4

A parametric test for correlation when data is interval level.

Question 5

What is the related t-test used for?

Answer 5

A parametric test for difference between two sets of scores. Data must be interval with a related design, i.e., repeated measures or matched pairs.

Question 6

What is the Sign test used for?

Answer 6

A statistical test used to analyze the difference in scores between related items (e.g., the same participant tested twice). Data should be nominal or better.

Question 7

What is Spearman’s rho used for?

Answer 7

A test for correlation when data is at least ordinal level.

Question 8

What is the unrelated t-test used for?

Answer 8

A parametric test for difference between two sets of scores. Data must be interval with an unrelated design, i.e., independent groups.

Question 9

What is the Wilcoxon test used for?

Answer 9

A test for a significant difference between two sets of scores. Data should be at least ordinal level using a related design (repeated measures).

Question 10

What are the three levels of measurement?

Answer 10

Nominal, ordinal, and interval.

Question 11

What is nominal data?

Answer 11

Data represented in the form of categories. For example, classifying people into categories like those who like cats, dogs, or neither.

Question 12

What is ordinal data?

Answer 12

Data that is ordered in some way, such as rating how much someone likes psychology on a scale from 1 to 10. However, the intervals between the numbers are not necessarily equal.

Question 13

What is interval data?

Answer 13

Data based on numerical scales with equal intervals and a true zero point. Examples include reaction times or temperature measurements.

Question 14

What is the appropriate measure of central tendency for nominal data?

Answer 14

Mode.

Question 15

What is the appropriate measure of central tendency for ordinal data?

Answer 15

Median.

Question 16

What is the appropriate measure of central tendency for interval data?

Answer 16

Mean.

Question 17

What is the appropriate measure of dispersion for ordinal data?

Answer 17

Range.

Question 18

What is the appropriate measure of dispersion for interval data?

Answer 18

Standard deviation.

Question 19

What is the key difference between related and unrelated designs?

Answer 19

In related designs (repeated measures or matched pairs), the same or matched participants are used in each condition. In unrelated designs (independent groups), different participants are used in each condition.

Question 20

What are parametric tests, and which tests fall under this category?

Answer 20

Parametric tests are statistical tests that require interval data and assume a normal distribution. Examples include the related t-test, unrelated t-test, and Pearson’s r.