9.2 Selection Control

Control variables:

There may be a need to interview some respondents in a specific order. For example, letters may need to be posted to respondents and these may not arrive for some time. In this situation the START variable in the CONFID data set may be set to the earliest interviewing date and time for each respondent. These respondents will not appear in the CATI interviewers' pull-down list and not be available to the IVR system until the START date and time has passed.

If the interviews for certain cases are to be prevented indefinitely, the SELECTED variable in CONFID or CONTROL may be set to 0. These respondents will not appear in the CATI interviewers' pull-down list and not be available to the IVR system until the SELECTED variable is reset to one.

If the interviews for certain cases are to be prevented because of ineligibility, the ELIGIBLE variable may be set to a positive value. These respondents will not appear in the CATI interviewers' pull-down list and not be available to the IVR system until the ELIGIBLE value is reset to zero.

Interviewer's Pull-down List:

By default, the interviewer's pull-down list shows the IDs and names of respondents. The names can be suppressed by setting the NONAME option in the TITL item to ``NONAME''.

Which IDs appears in the pull-down list is also controlled by the STATUS variable. The effect of the STATUS variable on the pull-down list is controlled by the $pulldfm. format. This format maps the status codes to the character strings, `IN' or `OUT'. For example, the $pulldfm. specifies that answering machine cases should remain in the pull-down list while refusals do not re-appear. This format also ensures that completed cases with status code CQ are not displayed. By editing the $pulldfm. format definition this default behaviour can be altered. To change the format for all projects, edit the definition that appears in the file \GEIS\BIN\FORMATS.SAS. Do not delete status codes or add new ones.

Updating External data sets:

The script item ``U'' option may be used for some item types to allow automatic updates of external data sets. The updating occurs when an interview ends. Refer to the file \GEIS\BIN\GEIS.TXT for the syntax of the ``U'' option.

For example, if a CHCE item has the ``U'' option set, then the value of the selected answer-option will be written to the external data set.

External-updating is carried out by locating a specified variable in the external data set and by matching on the respondent's ID. The external variable must match the data type of the item: numeric or character. As an alternative matching method, a logical expression can be used to identify the records to update.

To use updating specify the ``U'' option in the item header line, and the name of the external data set and variable at the appropriate part of the item definition; this is just before the end of the item.

As an example of where external-updating may be used, suppose two surveys of the same respondents run simultaneously, but it is essential that the interview in one survey must precede the interview in the other survey. The procedure to set this up is given below.

• The first survey is called Survey A and the second is Survey B.

• Ensure a libname is created in the Survey A project that points to the location of Survey B's data sets. For this example, the libname is called SVYB.

• In Survey B, initialise the SELECTED variable to 0. This can be done when creating the CONFID data set. This ensures that none of the respondents in Survey B will be prematurely interviewed.

• In Survey A, select an item that is to use external updating. It will be used to update the SELECTED variable in Survey B from 0 back to 1. Here it is assumed that a CHCE item is used.

• The CHCE item should have a question like

  ``Would it be all right if we rang you back in 2 weeks? YES or NO.''

• In the CHCE script item specify option codes to be 1 and 0 with corresponding texts `Yes' and `No'.

• In the script CHCE item, specify the ``U'' option in the item's header line.

• Also specify SVYB.CONTROL data set of Survey B as the external data set and SELECTED as the external variable.

• When a Survey A interview ends the answer to the CHCE item GEIS will update the SELECTED variable in Survey B's SVYB.CONTROL data set.

• Since the SELECTED variable now has a non-zero value the respondent's record will appear in Survey B's pull-down list and an interview may proceed.

RDD:

The current version of GEIS does not implement RDD.