1. Analyses using SPSS version 19
Chiara Haller, Harvard University

2. Introduction to SPSS (Andy Field)
Objectives
Knowledge:
How to use statistical analyses logically
How to create/structure a dataset
How to clean up the dataset
How to create frequency tables
Descriptive statistics:
Graphs (box-plot, dispersion diagrams)
Stratify the analysis
Literature:
Introduction to SPSS (Andy Field)

3. Data acquisition Name Date of Birth Weight/height Sex
Type it directly into SPSS?
Into Excel and - Import the data Copy the data into SPSS
Whatever you decide, keep a back up of your original dataset!!

5. Missing data
Input a value which must not be confused with any other value.
For example giving it a coding which does not exist in the rest of the data (i.e., -99).
Attention: Don’t forget to tell SPSS that these are missings! means without correct coding

6. The Compute function Calculate scores on behalf of existing variables
Example: Calculate BMI on behalf of the variables weight and height

7. Commande RECODE Recode Variables
Example: Recode height into 3 categories

8. The syntax It’s possible to keep all the analyses in a file
Instead of OK, press PASTE, and your commands are being opened as syntax, which can now be saved.
There are 3 windows you work with on SPSS:
Dataset: Variable view, data view
Output
Syntax
Each of these windows can be saved.

9. Descriptive statistics
Mean
Variance / standard deviation
Minimum / Maximum
… (click options for more)

13. Box-plot ¼ Extreme Values Upper quartile (3rd quartile) Mediane
¼ (top 25%)
Extreme Values
Mediane
Lower quartile
(1st quartile
Upper quartile
(3rd quartile)
«interquartile range»
¼ (bottom 25%)
Minimal Value

16. Scatter Plot

19. Stratify the analysis
It is often useful to split a sample in several sub-samples
Three possibilities:
Split the file
Select the preferred observations
Perform the analysis by stratifying the variable

20. Split files
Exercise:
Re-analyze the descriptive statistics

21. Select the preferred observations
Exercise:
Re-analyze the descriptive statistics

22. THE END