be found in Bethlehem and Hofman (2006).
The new group of activities was implemented in a so‐called CADI system. CADI stands for computer‐assisted data input. The CADI system was designed for use by the workers in the subject‐matter departments. Data could be processed in two ways by this system:
Heads‐up data entry. Subject‐matter employees worked through a pile of forms with a microcomputer, processing the forms one by one. First, they entered all data on a form, and then they activated the check option to test for all kinds of errors. Detected errors were reported on the screen. Errors could be corrected by consulting forms or by contacting the suppliers of the information. After elimination of all errors, a “clean” record was written to file. If employees could not produce a clean record, they could write the record to a separate file of “dirty” records to deal with later.
Heads‐down data entry. Data typists used the CADI system to enter data beforehand without much error checking. After completion, the CADI system checked in a batch run all records and flagged the incorrect ones. Then subject‐matter specialists handled these dirty records one by one and correct the detected errors.
To be able to introduce CADI on a wide scale in the organization, a new standard package called Blaise was developed in 1986. The basis of the system was the Blaise language, which was used to create a formal specification of the structure and contents of the questionnaire.
The first version of the Blaise system ran on networks of microcomputers under MS‐DOS. It was intended for use by the people of the subject‐matter departments; therefore no computer expert knowledge was needed to use the Blaise system.
In 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
