1. RISKY SHIFT:
DATA ANALYSIS
Week 6 Practical

2. LECTURE 1 PRACTICAL WEEK 1 WEEK 2 WEEK 3 WEEK 4 WEEK 5 WEEK 6 WEEK 7
RISKY SHIFT
WEEK 5 PRACTICAL
LECTURE 1
PRACTICAL
WEEK 1
NO LECTURE
NO PRACTICAL
WEEK 2
NONPARAMETRICS 1
1ST PRACTICAL
WEEK 3
NONPARAMETRICS 2
1ST ANALYSIS
WEEK 4
1ST ANALYSIS + PROBLEMS 1
WEEK 5
SAMPLING DISTRIBUTIONS
2ND PRACTICAL
WEEK 6
HYPOTHESIS TESTING
2ND ANALYSIS + SOLUTIONS 1
WEEK 7
RELATED T-TEST
2ND ANALYSIS + PROBLEMS 2
WEEK 8
INDEPENDENT T-TEST
3RD PRACTICAL
WEEK 9
INDEPENDENT ANOVA
3RD ANALYSIS + SOLUTIONS 2
WEEK 10
DEPENDENT ANOVA
3RD ANALYSIS + PROBLEMS 3

3. BY THE END OF THE SESSION, YOU SHOULD BE ABLE TO:
RISKY SHIFT
LEARNING OUTCOMES
BY THE END OF THE SESSION, YOU SHOULD BE ABLE TO:
Use SPSS to test the first, second and third experimental hypotheses of Risky Shift experiment and produce related graphs.
Experience terror as you try to battle with the graphing capabilities of SPSS 16.
Sigh with gentle satisfaction at the ease with which Excel will help you out with graphs.
Make a start on writing up your RESULTS and DISCUSSION sections for your lab report.

4. The first 2 columns show subject id and group membership.
RISKY SHIFT
RESULTS
The first 2 columns show subject id and group membership.
These columns show mean risk score at PRE, GROUP and POST.

5. RATINGS + WITHIN Ss + 3(+) GROUPS Friedman’s test
RISKY SHIFT
RESULTS
Q1: Is the average level of risk different across the PRE, GROUP and POST assessments?
RATINGS + WITHIN Ss + 3(+) GROUPS
Friedman’s test
First, we need to see whether there is any difference at all between the three groups, hence Friedman’s test.
In SPSS, Friedman’s test is hidden away underneath nonparametric tests > K related samples.

6. Put premean, grpmean and postmean all into the test variable box.
RISKY SHIFT
RESULTS
Q1: Is the average level of risk different across the PRE, GROUP and POST assessments?
RATINGS + WITHIN Ss + 3(+) GROUPS
Friedman’s test
SPSS would like to know what the test variables are, and in our case we have three.
Put premean, grpmean and postmean all into the test variable box.
Under Test Type, make sure the Friedman test is ticked because there are other tests you can do.

7. SPSS provides us with the mean ranks for each of the three groups.
RISKY SHIFT
RESULTS
Q1: Is the average level of risk different across the PRE, GROUP and POST assessments?
RATINGS + WITHIN Ss + 3(+) GROUPS
Friedman’s test
SPSS provides us with the mean ranks for each of the three groups.
The test statistics box confirms our N, the chi-square value, the degrees of freedom (groups – 1) and the significance level.
X2 (2) = 39.77, p < .001
The significance of this first test gives us the justification for going on to do the subsequent tests.

8. RATINGS + WITHIN Ss + 2 GROUPS Wilcoxon test
RISKY SHIFT
RESULTS
Q2: Is the average level of risk recorded in the PRE assessment different from the risk recorded in the GROUP assessment?
RATINGS + WITHIN Ss + 2 GROUPS
Wilcoxon test
Second, we need to see whether there is any difference between PRE and GROUP, hence Wilcoxon test.
In SPSS, Wilcoxon test is hidden away underneath nonparametric tests > 2 related samples.

9. Put premean and grpmean into the test pair(s) box.
RISKY SHIFT
RESULTS
Q2: Is the average level of risk recorded in the PRE assessment different from the risk recorded in the GROUP assessment?
RATINGS + WITHIN Ss + 2 GROUPS
Wilcoxon test
Again, SPSS would like to know what the test variables are, and in our case we have a pair of variables.
Put premean and grpmean into the test pair(s) box.
Under Test Type, make sure the Wilcoxon test is ticked because there are other tests you can do.

10. RATINGS + WITHIN Ss + 2 GROUPS Wilcoxon test
RISKY SHIFT
RESULTS
Q2: Is the average level of risk recorded in the PRE assessment different from the risk recorded in the GROUP assessment?
RATINGS + WITHIN Ss + 2 GROUPS
Wilcoxon test
SPSS provides us with the positive, negative and tied ranks for variable pair.
SPSS provides the Wilcoxon in the form of a z score to be reported as:
Wilcoxon z = -5.18, p < .001, n = 41
Why 41 and not 48?
SPSS ignored tied ranks…

11. RATINGS + WITHIN Ss + 2 GROUPS Wilcoxon test
RISKY SHIFT
RESULTS
Q3: Is the average level of risk recorded in the POST assessment different from the risk recorded in the PRE assessment?
RATINGS + WITHIN Ss + 2 GROUPS
Wilcoxon test
Second, we need to see whether there is any difference between POST and PRE, hence Wilcoxon test.
In SPSS, Wilcoxon test is hidden away underneath nonparametric tests > 2 related samples.

12. Put premean and postmean into the test pair(s) box.
RISKY SHIFT
RESULTS
Q3: Is the average level of risk recorded in the POST assessment different from the risk recorded in the PRE assessment?
RATINGS + WITHIN Ss + 2 GROUPS
Wilcoxon test
Again, SPSS would like to know what the test variables are, and in our case we have a pair of variables.
Put premean and postmean into the test pair(s) box.
Under Test Type, make sure the Wilcoxon test is ticked because there are other tests you can do.

13. RATINGS + WITHIN Ss + 2 GROUPS Wilcoxon test
RISKY SHIFT
RESULTS
Q3: Is the average level of risk recorded in the POST assessment different from the risk recorded in the PRE assessment?
RATINGS + WITHIN Ss + 2 GROUPS
Wilcoxon test
SPSS provides us with the positive, negative and tied ranks for variable pair.
SPSS provides the Wilcoxon in the form of a z score to be reported as:
Wilcoxon z = -5.15, p < .001, n = 40
Why 40 and not 48?
SPSS ignored tied ranks…

14. …but what are the direction of these effects?
RISKY SHIFT
RESULTS
Q1: Is the average level of risk different across the PRE, GROUP and POST assessments?
YES.
Friedman's test X2 (2) = 39.77, p < .001
Q2: Is the average level of risk recorded in the PRE assessment different from the risk recorded in the GROUP assessment?
INDEED.
Wilcoxon z = -5.18, p < .001, n = 41
Q3: Is the average level of risk recorded in the POST assessment different from the risk recorded in the PRE assessment?
Wilcoxon z = -5.15, p < .001, n = 40
QUITE RIGHT.
…but what are the direction of these effects?

15. DOWNLOAD AND SAVE THE FILE ‘RISKYINEXCEL’
RISKY SHIFT
RESULTS
DOWNLOAD AND SAVE THE FILE ‘RISKYINEXCEL’
To calculate mean:
AVERAGE(cellab:cellcd)
To calculate standard deviation:
STDEV(cellab:cellcd)
To calculate standard error:
=STDEV(cell) / sqrt (no. observations)
To start graphing:
Select means and labels

16. RISKY SHIFT
RESULTS
COLUMN

17. RISKY SHIFT
RESULTS
NEXT

18. RISKY SHIFT
RESULTS
MODIFY

19. RISKY SHIFT
RESULTS
DOUBLE CLICK COLUMNS

20. RISKY SHIFT
RESULTS
ADD CUSTOM +/- (S.E.)

21. RISKY SHIFT
RESULTS
LOW
HIGH
Q2: Is the average level of risk recorded in the PRE assessment different from the risk recorded in the GROUP assessment?
Q3: Is the average level of risk recorded in the POST assessment different from the risk recorded in the PRE assessment?
PRE < GROUP
PRE < POST
Lower risk in PRE
Lower risk in PRE

22. BY THE END OF THE SESSION, YOU SHOULD BE ABLE TO:
RISKY SHIFT
LEARNING OUTCOMES
BY THE END OF THE SESSION, YOU SHOULD BE ABLE TO:
Use SPSS to test the first experimental hypothesis of the Risky Shift experiment and produce a related graph.
Use SPSS to test the second experimental hypothesis of the Risky Shift experiment and produce a related graph.
Use SPSS to test the third experimental hypothesis of the Risky Shift experiment and produce a related graph.
Make a start on writing up your RESULTS and DISCUSSION sections for your lab report.

23. Why have I done these particular statistical tests?
RISKY SHIFT
DISCUSSION
GET TOGETHER IN GROUPS OF THREE OR FOUR AND REFLECT ON TODAY’S EXPERIENCE USING THE FOLLOWING QUESTIONS
Why have I done these particular statistical tests?
What do the data actually tell me with respect to my experimental hypotheses?
What implications do the data have for the studies outlined in the intro?