In the 'EDIT' - 'Questionnaire' tab, where you can edit the question, you can choose on the right menu next to the question, in the 'Basic' tab, to offer the respondents the option to choose among default missing values:
- Don't know (-99): the person did not know the answer to the question;
- Refused (-98): the person refused to answer the question;
- Invalid (-97): the person replied with an invalid answer;
- None of the above (-96): none of the above-mentioned answers applies to the person.
You can rename the default missing values by clicking on an individual category.
At the same time, you have additional options for the display of missing values for the respondents on the right side of the question. You can specify that these answers will appear for respondents only in the case when they do not answer the question. In this case, the question should be set as mandatory with a hard or soft reminder (choose one of the options above in the option 'Mandatory question:'). When you turn on a soft or hard reminder, you activate the options below:
- show option "Invalid" on alert;
- show option "Refused" on alert;
- show option "Don’t know" on alert.
If you check the option ‘Show the option "Don’t know" on alert:’ the respondent will see this answer only in case he does not answer the question, which will be indicated by clicking on the 'Next Page'.
Missing values (as described above) have negative values in the database and are excluded from the analysis by default (but can also be included in the analysis). Missing values can be viewed in the 'ANALYSE' - 'Statistics' in the Descriptives, Frequencies and Crosstabs. Some analyses (e.g. Averages) also do not take some other missing responses into account.