Data: Statistical Tests

Question 1

What are the different tests

Answer 1

• Sign test
• Chi-squared test
• Mann-Whitney U test
• Wilcoxon Matched Pairs Signed Ranks Test
• Spearman’s Rho test

Question 2

How would you know which test is appropriate to use

Answer 2

1) based on level of measurement (nominal, ordinal….)
2) based on the experimental design used (only relevant for experiments)
3) based on what it is testing for (difference or relationship)

—> remember: No I Can C MRS Will Smith

Question 3

What’s the appropriate test to use if:
1) Nominal data
2) testing for difference
3) Repeated measures design

Answer 3

Sign-test

Question 4

How do you calculate the critical value for a Chi-squared test

Answer 4

• find out direction of hypothesis (one/two-tailed), level of significance (the probability, e.g. p<0.05), and number of participants
• then calculate the Df (degrees of freedom), by doing number of cells DIVIDED by (rows-1) x (columns-1)
• then use this to find the critical value on a critical values table

Question 5

How do you calculate the critical value for a Spearman’s ranked test

Answer 5

• find out direction of hypothesis (one/two-tailed), level of significance (the probability, e.g. p<0.05), and number of participants
• using the number of participants, find the critical value on a critical values table

Question 6

How do you calculate the critical value for a Mann-Whitney U test

Answer 6

• find out direction of hypothesis (one/two-tailed), level of significance (the probability, e.g. p<0.05), and number of participants in both conditions
• N1 (for IV1) and N2 (for IV2)
• then use these 2 values to find the critical value on the critical values table

Question 7

How do you calculate the critical value for a Sign test

Answer 7

• find out direction of hypothesis (one/two-tailed), level of significance (the probability, e.g. p<0.05), and total number of differences
• e.g. you work this out as shown in image
• then use this value to find the critical value on the critical values table

Question 8

How do you calculate the critical value for a Wilcoxon test

Answer 8

• find out direction of hypothesis (one/two-tailed), level of significance (the probability, e.g. p<0.05), and total number of differences
• e.g. you work this out as shown in image
• then use this value to find the critical value on the critical values table

Question 9

If the observed value is greater than or equal to the critical value, which statistical test has an observed significance

Answer 9

• spearman’s
• chi-squared

Question 10

If the critical value is greater than or equal to the observed, which statistical test has an observed significance

Answer 10

• Mann-Whitney U
• Sign test
• Wilcoxon

Question 11

• There will be a positive correlation between a person’s height, and their reaction time. Participants: 7 men. Observed value: +0.699
• give a model answer for which hypothesis do you accept/reject

Answer 11

• the results are not significant because the observed value of +0.699 was smaller than the critical value of 0.714 for a one-tailed test at p<0.05
• this means that we accept the null hypothesis and reject the alternative hypothesis because…
• there is no significant difference in a person’s height and their reaction time, and the results are likely to be due to chance