By default, all questions must be answered before the next question may be displayed. Numeric items that have not been asked contain a missing value, ` .' (a single decimal point) and character items contain a single space, ` '. Items that have been answered contain non-missing values, such as ``1'', ``34'', or the texts of open-ended answers. The script must be designed to take this into account.
Some respondents may refuse to answer specific questions or answer `Don't Know'. These cannot be left as missing responses since GEIS is designed to require answers to all logically related questions; i.e. if a question should be asked then an answer must be recorded. Instead Don't Know answers and Refusals are stored using special codes. This section describes how to assign codes for Refusals, but Don't Know answers may be handled in a similar fashion.
To allow for a question to be skipped without recording an answer, the script must incorporate a ``Refuse to answer'' option. This is done in CHCE items my adding an extra option to cover this situation. This option may have any code value but it is preferable to use the value .R. This value is entered into the script as a dot followed immediately by capital R.
It is treated identically to a missing value in most cases, but it is still distinguishable from an ordinary missing value. When the data are summarised, item non-response rates may be calculated by the proportion of .R values in eligible questions in a questionnaire domain.
The .R value may also be entered in other numeric types. It can be typed directly into NUM, NUMM, and TABL entry fields as dot (``.'') followed by ``R''.
The .R value may also be used in SPSs when referring o items that use it. For example, Q3 NE .R.
It cannot be used in OPEN items since this item type stores character data. In this case the interviewers should type in a code string, such as ``REFUSED''.
Similarly, a coding system can be used to handle `Don't knows'. It is suggested that .K be used, but local conventions may also be followed.