Statistical testing

Question 1

What is a significant result?

Answer 1

where there is a low probability that chance factors were responsible for any observed difference, correlation or association in the variables tested

Question 2

What do we do if our results are significant? (in relation to hypothesis)

Answer 2

we can reject our null hypothesis and accept our alternative hypothesis

Question 3

What p level do we use in psychology?

Answer 3

we use p < 0.05 (as it strikes a balance between making a type I and II error) but p < 0.01 is used in tests that could cause harm like introducing a new drug

Question 4

What is a type I error?

Answer 4

when the null hypothesis is rejected when it should have been accepted
(happens when a lenient significance level is used, an error of optimism)

Question 5

What is a type II error?

Answer 5

when the null hypothesis is accepted when it should have been rejected
(happens when a stringent significance level is used, an error of pessimism)

Question 6

When to use the sign test?

Answer 6

data is nominal and repeated measures has been used

Question 7

How to calculate the sign test?

Answer 7

Calculate the differences between the two results
Count the number of positive and negative differences, ignoring signs that have stayed the same
The calculated value for the sign test, S, is the number of times the least frequent value has occurred
Calculate the N value (the total number of value - values with no difference)
Use the N value to find the critical value of S at p<0.05
If S is smaller than the critical value reject the null hypothesis
If S is larger than the critical value accept the null hypothesis

Question 8

Unrelated V related design

Answer 8

unrelated - independent groups

related - matched pairs and repeated measures

Question 9

What has to be taken into account when choosing a statistical test?

Answer 9

the design
the type of data
whether a difference or correlation is being measured

Question 10

What are the tests of association/correlation?

Answer 10

Chi-squared
Spearman’s Rho
Pearson’s R

Question 11

What test of association/correlation uses nominal data?

Answer 11

Chi-squared

Question 12

What test of association/correlation uses ordinal data?

Answer 12

Spearman’s Rho

Question 13

What test of association/correlation uses interval data?

Answer 13

Pearson’s R

Question 14

What are the three types of data?

Answer 14

Nominal
Interval
Ordinal

Question 15

What are the tests of difference used in an unrelated experiment?

Answer 15

Chi-squared
Mann-whitney
Unrelated t-test

Question 16

What are the tests of difference used in a related experiment?

Answer 16

Sign test
Wilcoxon
Related t-test

Question 17

What test of difference is used for an unrelated design and nominal data?

Answer 17

Chi-squared

Question 18

What test of difference is used for an unrelated design and ordinal data?

Answer 18

Mann Whitney

Question 19

What test of difference is used for an unrelated design and interval data?

Answer 19

Unrelated t-test

Question 20

What test of difference is used for a related design and nominal data?

Answer 20

Sign test

Question 21

What test of difference is used for a related design and ordinal data?

Answer 21

Wilcoxon

Question 22

What test of difference is used for a related design and interval data?

Answer 22

Related t-test

Question 23

How to know whether the calculated value has to be greater than or less than to be significant?

Answer 23

Rule of R
if there is an R in the name of the statistical test then the calculated value has to be gReater or equal to to critical value for results to be significant
if there is no R in the name of the test then the calculated value has to be less than or equal to the critical value for it to be significant