Inferential Statistics

Question 1

What is a hypothesis?

Answer 1

A hypothesis is a testable statement.

Question 2

What is Probability?

Answer 2

Probability is the likelihood (chance) that any difference or relationship (correlation) between groups has occurred simply due to chance

Question 3

What percentage do Psychologists accept their alternative hypothesis as significant?

Answer 3

P value </= 0.05%

Question 4

What is a Type 1 error?

Answer 4

A ‘false positive’. Where psychologists accept the alternative hypothesis and reject the null hypothesis.

Question 5

What is a Type 2 error?

Answer 5

A ‘false negative’. Where psychologists accept the null hypothesis and reject the alternative

Question 6

What does a Sign Test tell you?

Answer 6

A Sign Test tells you if the difference is significant or if any change is down to chance.

Question 7

How do you carry out a Sign Test?

Answer 7

1. Find N - count how many participants are involved.
2. Work out the calculated value - Find the difference between values, work out which ones are minus and which one are adds and count them up. The smaller of the two is the calculated value.
3. Decide which type of test to use - one-tailed or two-tailed.
4. Compare your calculated value with your critical value. If the calculated value is less than or equal to the critical value then it is significant.

Question 8

How do you carry out a Sign Test?

Answer 8

1. Find N - count how many participants are involved.
2. Work out the calculated value - Find the difference between values, work out which ones are minus and which one are adds and count them up. The smaller of the two is the calculated value.
3. Decide which type of test to use - one-tailed or two-tailed.
4. Compare your calculated value with your critical value. If the calculated value is less than or equal to the critical value then it is significant.

Question 9

What do you need to know when choosing a statistical test?

Answer 9

What type of data?
Is it a test for difference or correlation?
What type of design is used?

Question 10

What are the 3 types of data (level of measurement)?

Answer 10

Nominal data, Ordinal data and Interval data.

Question 11

What is Nominal data?

Answer 11

A frequency count for different categories - e.g The Sign Test, counting negatives and positives.
Most basic level of measurement.

Question 12

What is Ordinal data?

Answer 12

When data is ranked in order but not on a universally agreed measure. Very subjective.

Question 13

What is Interval data?

Answer 13

Parametric. Each unit is the same value - e.g 1cm -2cm is the same as 99cm-100cm. Objective.

Question 14

What are related measures?

Answer 14

This includes matched pairs design and repeated measures.

Question 15

What are related measures?

Answer 15

This includes matched pairs design and repeated measures.

Question 16

What are unrelated measures?

Answer 16

Independent groups.

Question 17

What are unrelated measures?

Answer 17

Independent groups.

Question 18

What type of test is a Directional Hypothesis?

Answer 18

One-tailed test

Question 19

What type of test is a Non-Directional Hypothesis?

Answer 19

Two-tailed test

Question 20

When would you use a Chi-square test?

Answer 20

When it is a test of difference, nominal data, unrelated design.

Question 21

When would you use a Sign Test?

Answer 21

When it is a test of difference, related design and nominal data.

Question 22

When would you use a Mann-Whitney U test?

Answer 22

When it is a test of difference, ordinal data and unrelated design.

Question 23

When would you use Spearman’s Rho test?

Answer 23

Test of correlation, ordinal data.