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Data capture

This is the process by which data are transferred from a paper copy (questionnaires and survey responses) to an electronic file. The responses are then put into a computer.

Before this procedure takes place, the questionnaires must be groomed (prepared) for data capture. In this processing step, the questionnaire is reviewed by someone to ensure that all of the minimum required data have been reported, and that they are decipherable. This grooming is usually performed during extensive automated edits.

There are several methods used for capturing data:

• tally charts are used to record data such as the number of occurrences of a particular event and to develop frequency distribution tables. Tally charts are used only with small amounts of data. This form of data capture would never be used for a census. However, in the instance where a hand count is required (e.g., election ballots), a tally chart could be considered quite useful.

• batch keying is one of the oldest methods of data capture. It uses a computer keyboard to type in the data. This process is very practical for high-volume entry where fast production is a requirement. No editing procedures are necessary but there must be a high degree of confidence in the editing program. Also, validity and range edits need to be implemented to ensure quality keying. This does not mean the data are being re-edited, but if a field is numeric and alpha characters are entered instead, the error will be flagged. This approach can be beneficial when used for large surveys with many questions and edits.

• interactive capture is often referred to as intelligent keying. Usually, captured data are edited before they are imputed. However, this method combines data capture and data editing in one function. Although interactive capture is slower, it is a very effective approach to use when there is a lot of interdependency between questions. This process requires knowledge of editing procedures, as the errors need to be corrected right away. Interactive capture also reduces the number of documents handled, as the edits are made directly on a computer.

  The edits performed during an interactive capture can be preliminary data checks or basic edits (such as total, subtotal and value checks), or they can consist of full edits applied to the entire questionnaire. (One of these systems is referred to as the computer-assisted telephone interviewing process discussed in the chapter on Data collection).

• optical character readers or bar-code scanners, are able to recognize alpha or numeric characters. These readers scan lines and translate them into the program.

  These bar-code scanners are quite common and often seen in department stores. They can take the shape of a gun or a wand. The gun scanner is simple to program and can verify the validity of what has been scanned. The Census of Agriculture uses this scanning method for its document-control system. A printer prints out bar codes to label the questionnaires. Then the bar coder scans the label and translates the lines into numbers that are entered into the document-control file.

  The wand or pen type of scanner reads identification numbers. This scanning method requires a slow and steady hand in order to ensure that the wand is aligned properly with the printed characters.

• magnetic recordings allow for both reading and writing capabilities. This method may be used in areas where data security is important. The largest application for this type of data capture is the PIN number found on automatic bank cards.

A computer keyboard is one of the best known input (or data entry) devices in current use. In the past, people performed data entry using punch cards or paper tape.

Some modern examples of data input devices are

• optical mark reader
• bar-code reader
• scanner used in desktop publishing
• light pen
• trackball
• mouse

Did you know that ...

• A new objective for 2001 was to create an image retrieval system giving access to the images (pictures) of all of the census questionnaires and visitation records, so that subsequent processes requiring access to original census forms would not have to handle the thousands of boxes and paper documents, as in previous censuses.
• Users will have access to more information free of charge on the internet through Statistics Canada's Website (www.statcan.ca).
• For the first time, the census collects information on same-sex couples, as well as information on language of work.
• The respondent's guide that previously accompanied the short questionnaire was no longer printed, saving some 215,460 kg of paper.
• Approximately 13.2 million questionnaires were keyed using 5 billion key strokes.
• Alternative means of collection and processing included the Internet, by which Canadians could file their questionnaires on-line; automated editing processes; and a computer-assisted telephone interview application to name several.

Once data have been entered into a computer database, the next step is ensuring that all of the responses are accurate. This method is known as data editing.