By default, the Variable Name is limited to 8 characters . SPSS will not permit the use of some characters. Although you can enter data using these default settings, it is easier in the long run if you work through these columns entering the specific characteristics of the particular variable. The default is for variable type is Numeric . Numeric refers to numbers.
String refers to actual words.
In most cases the default setting is used because numeric variables permit more statistical analysis. In this window, you also specify the Width and number of Decimal Places for the variable. The default for Variable Width is 8 characters. However 24.8 is four characters in width because you must count the decimal point as a character To determine the width of a variable, consider the maximum value that you are likely to obtain for a variable. If you were collecting data on patients' systolic blood pressure, you would probably specify width of variable as 3 because you are unlikely to obtain a value in the thousands.