Handbook of Web Surveys. Jelke Bethlehem
the Blaise philosophy, the first step in carrying out a survey was to design a questionnaire in the Blaise language. Such a specification of the questionnaire contains more information than a traditional paper questionnaire. It did not only describe questions, possible answers, and conditions on the route through the questionnaire but also relationships between answers that had to be checked.
Figure 1.6 contains an example of a simple paper questionnaire. The questionnaire contains one route instruction: persons without job are instructed to skip the questions about the type of job and income.
Figure 1.7 contains the specification of this questionnaire in the Blaise system. The first part of the questionnaire specification is the Fields section. It contains the definition of all questions that can be asked. A question consists of an identifying name, the text of the question as presented to the respondents, and a specification of valid answers. For example, the question about age has the name Age, the text of the question is “What is your age?” and the answer must be a number between 0 and 99.
Figure 1.6 A simple paper questionnaire
Figure 1.7 A simple Blaise questionnaire specification
The question JobDes requires a text not exceeding 20 characters. Income is a closed question. There are three possible answer options. Each option has a name (for example, Less20) and a text for the respondent (for example, “Less than 20,000”).
The second part of the Blaise specification is the Rules section. Here, the order of the questions is specified and the conditions under which they are asked. According to the rules section in Figure 1.7, every respondent must answer the questions SeqNum, Age, Sex, MarStat, and Job in this order. Only persons with a job (Job = Yes) have to answer the questions JobDes and Income.
The rules section can also contain checks on the answers of the questions. Figure 1.7 contains such a check. If people are younger than 15 years (Age < 15), then their marital status can only be not married (MarStat = NotMar). The check also contains texts that are used to display the error message on the screen (If respondent is younger than 15 then he/she is too young to be married!).
The rules section may also contain computations. Such computations could be necessary in complex routing instructions or checks or to derive new variables.
The first version of Blaise used the questionnaire specification to generate a CADI program. Figure 1.8 shows what the computer screen of this MS‐DOS program looked like for the Blaise questionnaire in Figure 1.7.
Figure 1.8 A Blaise CADI program
Since this program was used by subject‐matter specialists, only question names are shown on the screen shown in Figure 1.8. Additional information could be displayed through special keys. Note that the input fields for the questions Age and MarStat contain error counters. These error indicators appeared because the answers of the questions Age (2) and MarStat (Married) did not pass the check.
After Blaise had been in use for a while, it was realized that such a system could be made much more powerful. The questionnaire specification in the Blaise system contained all knowledge about the questionnaire and the data needed for survey processing. Therefore, Blaise should be capable to handle CAI.
Implementing CAI means that the paper questionnaire is replaced by a computer program containing the questions to be asked. The computer takes control of the interviewing process. It performs two important activities:
Route control. The computer program determines which question is to be asked next and displays that question on the screen. Such a decision may depend on the answers to previous questions. As a result, it is not possible anymore to make route errors.
Error checking. The computer program checks the answers as data are entered. Range checks are carried out immediately, as well as consistency checks after entry of all relevant answers. If an error is detected, the program produces an error message, and data must be corrected.
Use of computer‐assisted data collection has three major advantages. First, it simplifies the work of interviewer (for example, no more route control). Second, it improves the quality of the collected data. Third, data are entered in the computer during the interview resulting in a complete and clean record.
Figure 1.9 A Blaise CAPI program
Version 2 of Blaise was completed in 1988. It implemented CAPI. This is a form of face‐to‐face interviewing in which interviewers use a laptop computer to conduct the interview.
Figure 1.9 shows an example of a screen of a CAPI program generated by Blaise. The screen was divided in two parts. The upper part contains the current question to be answered (What kind of a job do you have?). After an answer had been entered, this question was replaced by the next question on the route.
Just displaying one question at the time gave the interviewers only limited feedback on where they are in the questionnaire. Therefore, the lower part of the screen displayed (in a very compact way) the current page of the questionnaire.
Statistics Netherlands started full‐scale use of CAPI in regular survey in 1987. The first CAPI survey was the Labor Force Survey. Each month, about 400 interviewers equipped with laptops visited 12,000 addresses. After a day of interviewing, the laptop was connected to a telephone modem. The data were transmitted to the office at night. In return, new addresses were sent to the interviewers. The next morning the laptop was prepared for a new day of interviewing.
CATI was introduced in 1990 on desktop computers. Interviewers called respondents from a central unit (call center) and conducted interviews by telephone. The interviewing program for CATI was the same as that for CAPI. An important new tool for CATI was a call scheduling system. This system took care of proper delivering busy numbers (try again shortly), no answers (try again later), appointments, etc.
By the very early 1990s, nearly all household surveys of Statistics Netherlands had become CAPI or CATI surveys. Surveys using paper forms had almost become extinct. Table 1.3 lists all major and regular household surveys at that time together with their mode of interviewing.