Title Detailed computations of questionnaire usability


In the 'STATUS' - 'Usable respondents' tab, you can turn on the display of detailed computations by clicking on the ‘Data table settings’ and selecting the 'Calculations' check box. The table displays values for the following calculations:


1. UNL – Unit Nonresponse Level. It is obtained by dividing the number of all variable nonresponse for each unit by the number of all variables that have been shown to this unit. Therefore, UNL for a respondent who answered all the questions in the survey is 0. The other extreme is the case where a respondent came to the end of the survey and the application recorded all variables as variable nonresponse, resulting in UNL = 1.


2. UML – Unit Missing-data Level, which represents the percentage of questions to which the respondent did not answer because they left the survey too soon (breakoff). Therefore, in calculating the UML, we take into account the UBL - Breakoff Unit Level, which reflects the share of pages of the questionnaire (i.e. share of the questions), which would have been displayed to the respondent after they had prematurely terminated the survey. For example, if a breakoff occurs after the respondent completed 10% of the questionnaire, then UBL is 0.9 or 90 %. Thus, we have data for the UNL and UBL and we can also calculate the UML: 

UML = UBL + (1 – UBL) × UNL = UBL + UNL – UBL × UNL


3. UCL – Unit Completeness Level is complementary to the corresponding value of the UML: 

UCL = (1 – UML) = 1 – UBL – UNL + UBL × UNL

If we take the example from the previous point with LBM = 0.9 and assume that the respondent answers to half of the 10% of the responses that were shown to him (UNL = 0.5), then UCL is 0.05 or 5%.


4. UIL - Unit Non-applicability level is calculated by dividing the total number of variables, where the condition (IF) for a given unit is not met (status -2) by the sum of the number of all variables that were shown to this unit and the total number of variables, where the condition (IF) for a given unit is not met. If the survey has 20 questions and the respondent answered 10 questions, and the remaining 10 questions were not shown because the respondent did not satisfy the condition, then the UIL is 0.5 or 50%.


5. UAQ – Unit Additional Questions is calculated by dividing the number of variables that a particular respondent was not shown because they were subsequently added to the questionnaire by the number of all variables. If a survey has 20 variables and we subsequently add 10 more variables, the UAQ for this respondent is 0.33 or 33%.


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Edit date 26.02.2015

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