Research methodology
120
Decimals
indicates the number of decimal places to be shown
. Click on in the first cell of the fourth column
.
Type 0 in this cell, or click on the down arrow twice to reduce the number shown to 0
Before continuing examine the range of data types that are available. Clicking on
any cell in the
Type column and then clicking on the
… symbol will show them.
The Comma, Dot and Scientific Notation options provide for numeric data in different formats.
The Date option allows calendar dates to be entered e.g. 24-05-95. The Dollar and Custom
currency options provide for currency data e.g. £24.99. The String option is often used to put
in comments for each observation; for instance you may wish to record the doctor who saw
each patient and enter ‘Dr Smith’ or ‘Dr Jones’ as text. The default data format is numeric and
most data is best entered in this format, using numeric codes. The use of other codes may
restrict the statistical techniques available: for example none of the statistical options at all
work with data in string format.
4. Missing values
SPSS is good at handling missing data; there are essentially two options for doing so:
Option 1: System-defined missing values
The system-defined value for missing data in SPSS is ‘.’. Missing values imported from other
software appear on the worksheet as ‘.’, and you can input missing values by entering the
full-stop (without quotes) manually.
These missing values are not included in the analysis and SPSS gives a useful summary of
missing values and numbers of patients included (the ‘case processing summary’) as part of
the output for all analyses.
However, you may wish to include missing values in some analyses, and it is also good
practice to record reasons for missing values if these are known. In this case option 2 is
preferable:
Dostları ilə paylaş: