Psyc.301
SPSS Lab Session
Spring 2014
Data screening & Transformation
Recode
– To recode negatively worded items
– To collapse continuous variables into categorical ones
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Recode into same variable
Recode into different variable
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Recoding negatively worded scale items
– Transform ─ Recode into SAME variables (to overwrite original data)
– Select variables and move it to Variables box ( k1, k6, k7, k8, k10, k13, k15, and
k16 in week3 dataset.sav data)
– Click on Old and New Values
– Type old value in old value box new value in new value box and click Add
– Repeat the last step for the remaining values to be changed
– Click on Continue and Ok
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To collapse a continuous variable
– Transform ─ Recode into different variables (to retain original data)
– Select variable and move it to Numeric Variable-Output Variable box
– Type a new name in name box and a new label in label box, and click on
change
– Click on Old and New Values
– Click on second Range and type the median in the box
– Type new value in new value box and click Add
– Click on third Range, type the median plus 1 in the box
– Type new value in new value box and click Add
– Click on Continue and Ok
Compute
• Usually to obtain composite scores of items
Example: kssc scale items.sav
• Compute if … («compute if certain condition is
met»)
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COMPUTE (example of calculating a total score)
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Transform ─ Compute variable
Type a name in Target Variable box
Select variables and move to Numeric expression box, click on +
Select other variables and repeat the same step by clicking on +
click on Ok
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New composite variable is added to the data
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COMPUTE IF…
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Transform ─ Compute variable
Type a name in Target Variable box
Select variables and move to Numeric expression box, click on +
Select other variables and repeat the same step by clicking on +
Click on If, select Include if case satisfies condition,
Select the relevant variable and move it to the box, select the required
operator button
– click on Continue and Ok
Descriptive statistics
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Mean
Mode
Median
Standard deviation
Normality measures: skewness kurtosis
Normal distribution
Negatively skewed distribution
Positively skewed distribution
Histogram
Data distribution
Select cases
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If you want to analyze only a part of the dataset which mets a certain condition
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Selection of specified cases using the If option
Selection of a random sample of cases using the Sample option
Selection of cases based on time or case range using the Range option
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Example: Select the first 5 cases for the analysis:
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Data ─ Select cases ─ If condition is satisfied ─ If
Select the relevant variable and move it to the box
Click on the relevant operator to add it into the box
Type if any other values are required (example: id<=5)
Click on Continue and Ok
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The cases after 5 are crossed in the data, analysis can be conducted by using only the first 5 cases
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Example 2: Selecting female cases
Example 3: Selecting those having depression scores above 16.