Name
The name of each SPSS variable in a given file must be unique; it must
start with a letter; it may have up to 8 characters (including letters,
numbers, and the underscore _ (note that certain key words are reversed and
may not be used as variable names, e.g., "compute", "sum", and so forth). To
change an existing name, click in the cell containing the name, highlight
the part you want to change, and type in the replacement. To create a new
variable name, click in the first empty row under the name column and type a
new (unique) variable name.
Notice that we can use "student_id" but not "student-id" and not "student id". The hyphen gets interpreted as subtraction (student minus id) by SPSS, and the space confuses SPSS as to how many variables are being named.
Type
The two basic types of variables that you will use are numeric and string. Numeric variables may only have numbers assigned. String variables may contain letters or numbers, but even if a string variable happens to contain only numbers, numeric operations on that variable will not be allowed (e.g., finding the mean, variance, standard deviation, etc...). To change a variable type, click in that cell on the grey box with ...
Clicking on this box will bring up the variable type menu:
If you select a numeric variable, you can then click in the width box or the decimal box to change the default values of 8 characters reserved to displaying numbers with 2 decimal places. For whole numbers, you can drop the decimals down to 0.
If you select a string variable, you can tell SPSS how much "room" to leave in memory for each value, indicating the number of characters to be allowed for data entry in this string variable.
Width
The width of a variable is the number of characters SPSS will allow to be
entered for the variable. If it is a numerical value with decimals, this
total width has to include a spot for each decimal, as well as one for the
decimal point. You can change a width by clicking in the width cell for the
desired variable and typing a new number or you can use the arrow keys at
the edge of the cell
Decimals
The decimals of a variable is the number of decimal places that SPSS will display. If more decimals have been entered (or computed by SPSS), the additional information will be retained internally but not displayed on screen. For whole numbers, you would reduce the number of decimals to zero. You can change the number of decimal places by clicking int he decimals cell for the desired variable and typing a new number or you can use the arrow keys at the edge of the cell
Label
The label of a variable is a string of text to indentify in more detail
what a variable represents. Unlike the name, the label is limited to 255
characters and may contain spaces and punctuation. For instance, if there is
a variable for each question on a questionnaire, you would type the question
as the variable label. To change or edit a variable label, simply click
anywhere within the cell.
Values
Although the variable label goes a long way to explaining what the
variable represents, for categorical data (discrete data of both nominal and
ordinal levels of measurement), we often need to know which numbers
represent which categories. To indicate how these numbers are assigned, one
can add labels to specific values by clicking on the ... box in the values
cell
Clicking here opens up the Value Labels dialogue box.
- Click in the Value field to type a specific numeric value
- Click in the Label field to type the corresponding label
- Click on the Add button to add this pair of value and label to the list
The real beauty of value labels can be seen in the Data View by clicking
on the "toe tag" icon in the tool bar
which
switches between the numeric values and their labels
Missing
We sometimes want to signal to SPSS that data should be treated as missing, even though there is some other numerical code recorded instead of the data actually being missing (in which case SPSS displays a single period -- this is also called SYSTEM MISSING data). In this example, after clicking on the ... button in the Missing cell, I declared "9", "99", and "999" all to be treated by SPSS as missing (i.e., these values will be ignored)
Columns
The columns property tells SPSS how wide the column should be for each variable. Don't confuse this one with width, which indicates how many digits of the number will be displayed. The column size indicates how much space is allocated rather than the degree to which it is filled.
Align
The alignment property indicates whether the information in the Data View
should be left-justified, right-justified, or centered
Measure
The Measure property indicates the level of measurement. Since SPSS does
not differentiate between interval and ratio levels of measurement, both of
these quantitative variable types are lumped together as "scale". Nominal
and ordinal levels of measurement, however, are differentiated
