To understand how an axis becomes a variable, look at the different types of element you can have and see how they appear in the SAS files. The simplest axis is one in which the elements are single-coded. Take sex as an example. The axis:

becomes:

In the axis, the element’s condition determines the code which represents the response in the data. In the variable, the values for each answer are determined solely by the element’s position in the axis: ‘Not stated’ is the third answer so it becomes value 3 in the SAS variable. However, if an element in the axis contains no respondents (because no one gave that answer), that element is ignored and subsequent elements are renumbered. Thus, if column 110 of the Quantum data file never contains a code 2, the SAS specification for sex is:

The base element in the axis definition is a count of respondents in the axis rather than an answer so it is ignored. Axes which contain only a base are ignored.

A similar thing happens with numeric data specified using the Quantum val statement. qtsas creates a format description for the variable listing the values present in the data. These will not be the numeric values in the Quantum data but codes allocated to those values according to the element’s position in the axis (and whether or not that element contains any respondents). qtsas then assigns this format to the variable, as shown below.

becomes:

The axis name has been truncated to five characters to make the format name. You might want to ensure that all the original Quantum axes have names of fewer than five characters to avoid duplicate names in the SAS data description (tmpxxy and tmpxxz would both become tmpxxfmt).

SAS does not handle multicoded data so qtsas converts it into the standard SAS format. When an axis is multicoded, qtsas creates as many variables as there are elements used in the axis. Each variable is named according to the axis name, but has a numeric suffix associated with the element’s position in the axis. For example, the multicoded axis:

is converted into five variables named _color1 to _color5. The variable names start with an underscore (_) indicating that they are derived variables rather than variables related directly to a Quantum axis.

Each variable has two values: 1 if the respondent gave that answer, or 0 if they did not. Since there are no other values, no entry is generated in the proc format section. Instead, the answers which the variables represent are defined in the format section as follows:

As with single-coded variables, any unused values are ignored and subsequent items are renumbered.

Sometimes responses are coded with numeric codes of more than one digit; for example, 500 for a VW Scirocco, 520 for an Audi Quattro. Axes for data of this type will often be set up with fld or bit statements. If so, qtsas deals with them in same way as for multicoded axes. Thus, the axis:

is converted into two variables _cars1 and _cars2 labeled with the element text defined in the axis:

If a respondent answers all questions in the questionnaire, the record will contain one value for each variable. If some questions are unanswered, or if filtering excludes a respondent from the axis, qtsas inserts a dot in the appropriate positions in the records. In SAS, the dot is called the missing value.

Quantum runs can be weighted. In Quantum, weights (apart from pre- and postweights) are defined in the tab section. qtsas converts the weighting matrix into a variable with a numeric suffix, and appends each respondent’s weight to the end of the record. Because the weight variable is not a bona fide Quantum axis, qtsas starts the variable name with an underscore. Thus, the statement:

appears at the end of the data list as _weight0, and records have either 100 or 200 as their last value, depending on whether the respondent is male or female.

For example:

The format definition for a weighting variable is the same as the variable name except that the underscore is replaced with an @ sign. If the run contains more than one weighting matrix, the second matrix is named @weight1, the third is named @weight2, and so on.

To transfer data in numeric variables to the SAS data file, you need to create a namedinc statement for each numeric variable. namedinc statements should be defined after any global titles but before your tab statements and are in the form:

namedinc data_spec [;options]

The data_spec can be anything which gives an integer or float result.

The options available are:

For example:

If, however, a numeric variable called shop does not exist, you can define it by specifying which columns it refers to. It could, for example, be written as:

If you do not specify a variable name (varname=), Quantum sets the name to the variable’s data_spec. If you do not assign a description to the variable (vartext=), Quantum makes the description the same as its name.

Numeric variables do not have a predefined set of values, so there is no proc format section. Instead, the variable is defined with a label statement:

and the exact value of the variable is placed in the appropriate place in each record.