RISKY SHIFT:

1
RISKY SHIFT DATA ANALYSIS
Week 6 Practical
2
WEEK 6 PRACTICAL
RISKY SHIFT
LECTURE 1
PRACTICAL
WEEK 1
NO LECTURE
NO PRACTICAL
WEEK 2
NONPARAMETRICS 1
1ST PRACTICAL
WEEK 3
NONPARAMETRICS 2
1ST ANALYSIS IN SPSS
WEEK 4
1ST ANALYSIS BY HAND
SAMPLING DISTRIBUTIONS
WEEK 5
2ND PRACTICAL
WEEK 6
2ND ANALYSIS IN SPSS
HYPOTHESIS TESTING
WEEK 7
RELATED T-TEST
2ND ANALYSIS BY HAND
WEEK 8
3RD PRACTICAL
INDEPENDENT T-TEST
INDEPENDENT ANOVA
WEEK 9
3RD ANALYSIS IN SPSS
WEEK 10
DEPENDENT ANOVA
NO PRACTICAL
3
LEARNING OUTCOMES
RISKY SHIFT
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.
Make a graph to show the results with Excel 2007.
Think about the meaning(s) of your results, how
they relate to past research and how they could
be flawed.
Make a start on writing up your RESULTS and
DISCUSSION sections for your lab report.
4
RESULTS
RISKY SHIFT
These columns show mean risk score at PRE, GROUP
and POST.
The first 2 columns show participant id and group
membership.
5
RESULTS
RISKY SHIFT
Q1 Is the average level of risk different across
the PRE, GROUP and POST assessments?
Friedmans test
RATINGS WITHIN Ss 3() GROUPS
First, we need to see whether there is any
difference at all between the three groups, hence
Friedmans test.
In SPSS, Friedmans test is hidden away
underneath nonparametric tests gt K related
samples.
6
RESULTS
RISKY SHIFT
Q1 Is the average level of risk different across
the PRE, GROUP and POST assessments?
Friedmans test
RATINGS WITHIN Ss 3() GROUPS
SPSS would like to know what the test variables
are, and in our case we have three.
Put premean, groupmean 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
RESULTS
RISKY SHIFT
Q1 Is the average level of risk different across
the PRE, GROUP and POST assessments?
Friedmans test
RATINGS WITHIN Ss 3() GROUPS
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 lt .001
The significance of this first test gives us the
justification for going on to do the subsequent
tests.
8
RESULTS
RISKY SHIFT
Q2 Is the average level of risk recorded in the
PRE assessment different from the risk recorded
in the GROUP assessment?
Wilcoxon test
RATINGS WITHIN Ss 2 GROUPS
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 gt 2 related samples.
9
RESULTS
RISKY SHIFT
Q2 Is the average level of risk recorded in the
PRE assessment different from the risk recorded
in the GROUP assessment?
Wilcoxon test
RATINGS WITHIN Ss 2 GROUPS
Again, SPSS would like to know what the test
variables are, and in our case we have a pair of
variables.
Put premean and groupmean 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
RESULTS
RISKY SHIFT
Q2 Is the average level of risk recorded in the
PRE assessment different from the risk recorded
in the GROUP assessment?
Wilcoxon test
RATINGS WITHIN Ss 2 GROUPS
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 lt .001, n 41
Why 41 and not 48? SPSS ignored tied ranks
11
RESULTS
RISKY SHIFT
Q3 Is the average level of risk recorded in the
POST assessment different from the risk recorded
in the PRE assessment?
Wilcoxon test
RATINGS WITHIN Ss 2 GROUPS
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 gt 2 related samples.
12
RESULTS
RISKY SHIFT
Q3 Is the average level of risk recorded in the
POST assessment different from the risk recorded
in the PRE assessment?
Wilcoxon test
RATINGS WITHIN Ss 2 GROUPS
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
RESULTS
RISKY SHIFT
Q3 Is the average level of risk recorded in the
POST assessment different from the risk recorded
in the PRE assessment?
Wilcoxon test
RATINGS WITHIN Ss 2 GROUPS
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 lt .001, n 40
Why 40 and not 48? SPSS ignored tied ranks
14
RESULTS
RISKY SHIFT
Q1 Is the average level of risk different across
the PRE, GROUP and POST assessments?
Friedman's test X2 (2) 39.77, p lt .001
YES.
Q2 Is the average level of risk recorded in the
PRE assessment different from the risk recorded
in the GROUP assessment?
YES.
Wilcoxon z -5.18, p lt .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 lt .001, n 40
YES.
but what are the direction of these effects?
15
RESULTS
RISKY SHIFT
DOWNLOAD AND SAVE THE FILE RISKYINEXCEL
To calculate mean AVERAGE(cellabcellcd)
To calculate standard deviation STDEV(cellabcel
lcd)
To calculate standard error (cellSTDEV)/sqrt
(no. observations)
To start graphing Select Insert ? Column ?
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RESULTS
RISKY SHIFT
SURPRISE! (So much easier than Excel 2003)
17
RESULTS
RISKY SHIFT

• MAKING ERROR BARS
• Select any part of the graph
• Click on Layout (under Chart Tools on the
  toolbar)
• Then Error Bars
• Then More Error Bars Options

Make sure you select all three standard errors.
18
RESULTS
RISKY SHIFT
TIDYING UP Get rid of any unnecessary bits (e.g.
background lines, legend) Change colours to
greyscale Change the y-axis to reflect full range
of possible answers Make sure you have axis labels
19
RESULTS
RISKY SHIFT
LOW
HIGH
Q3 Is the average level of risk recorded in the
POST assessment different from the risk recorded
in the PRE assessment?
Q2 Is the average level of risk recorded in the
PRE assessment different from the risk recorded
in the GROUP assessment?
PRE gt GROUP
PRE gt POST
Lower risk (higher score) in PRE
Lower risk (higher score) in PRE
20
DISCUSSION
RISKY SHIFT
GET TOGETHER IN GROUPS OF THREE OR FOUR AND
REFLECT ON TODAYS EXPERIENCE USING THE FOLLOWING
QUESTIONS
Are there any problems with interpreting the data?
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?
21
LEARNING OUTCOMES
RISKY SHIFT
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.
Make a graph to show the results with Excel 2007.
Think about the meaning(s) of your results, how
they relate to past research and how they could
be flawed.
Make a start on writing up your RESULTS and
DISCUSSION sections for your lab report.