DATA COLLECTION METHODS
There are a number of methods available to the researcher for collecting data. The commonly used data collection methods can be divided into three basic types:
- personal interview,
- self enumeration, and
- telephone interview.
These three manual, paper- based types have corresponding electronic methods:
- computer assisted personal interviewing (CAPI),
- computer assisted self- interviewing (CASI) which includes web and email forms, and
- computer assisted telephone interviewing (CATI).
A further data collection method not covered here is the use of existing data sources, such as administrative files. The success of the survey will depend to a large extent on the suitability of the data collection method chosen. The factors discussed below need to be considered when determining a data collection method that is appropriate for the survey requirements.
FACTORS AFFECTING CHOICE OF COLLECTION METHOD
Complexity of Topic
The depth and complexity of the topic to be covered and, in particular, the nature and form of the questions, will often dictate the collection method to be employed. The likely quality or length of the response sought may also influence the choice of collection method. For instance, it is often difficult to obtain answers to complex questions using telephone surveys, whereas self-administered surveys can include detailed explanatory notes, and personal interviews with the aid of such features as show-cards can often yield a more detailed response. For surveys with complicated sequencing, an electronic version that performs this sequencing well is preferable to a paper version.
Types of data
The kind of topics that can be properly covered vary across data collection method. For sensitive topics, self-administered methods are generally preferred to interviews as they are seen as more private. Sometimes a face to face interview will include a self-administered module for this reason. Surveys which require respondents to check records before they can answer, or check with other people who may not be immediately available, should also use self-administered methods. For this reason a telephone survey might involve mailing a form out for respondents to complete, but ask them to read out their answers over the phone.
The quality and reliability of survey data can be significantly affected by the degree of response to a survey. Although it is very rare to achieve a 100 per cent response rate for any survey, the choice of collection method can significantly influence the response rate obtained. Personal interviews can achieve a better response rate than mail surveys or telephone surveys because it is more difficult to refuse to a person's face. However other factors such as whether the survey is compulsory, whether it is repeated and how the follow-up is conducted can mediate the effect of method on response.
How the collection method fits in with the life style or working style of the respondent should influence what collection method will be used, as this will increase respondent motivation. For example, the Retail Business Survey works well as a CATI survey in part because the respondents do much of their business over the phone and therefore are comfortable with this method. Some respondents have a strong preference for completing their forms electronically, and since the Electronic Transaction Act (July 2001) came into effect, respondents can insist on their right to do this for ABS surveys.
When human resources, money or time are limited, the researcher may choose to use a less appropriate collection method in order to boost the number of responses or get the responses more quickly. Such an option is often in conflict with the quality requirements of the survey. To compromise, a planned reduction in data quality, a reduction in coverage or using a less systematic way of choosing a sample, might be alternatives presented to the researcher. The researcher might also seek resources or cost savings elsewhere.
Sampling Frame and the Population
The type and quality of the sampling frame may influence the choice of collection method. For example, if the target population includes the homeless, a mail survey is not suitable. The characteristics of the population may also influence the collection method. If we are interested in doing a survey which includes shift workers and other people who are not home during the times an interviewer could reach them, then a mail survey would be more appropriate than an interview.
Personal Interview - Face to Face
In the ABS personal interviews are used mostly for household social surveys. Personal interviews involve a trained interviewer going to the potential respondent, asking the questions and recording the responses. Because of the interaction involved when the interviewer is present, this method of data collection is effective in terms of:
- establishing rapport,
- high response rates,
- conducting surveys which require complex sequencing.
Personal interviews are however very expensive to conduct. There are costs involved in personnel, time, and other resources required to obtain, train, and manage an interviewer workforce. Travelling from one respondent to another is another cost component in personal interview and is especially problematic when repeat visits are necessary to catch the respondent while they are available. Data can possibly be subject to bias caused by the interviewer's appearance and attitude as well the way they phrase and rephrase questions and explanations. Also, the respondents may not feel free to disclose sensitive or private information to an interviewer.
Computer-Assisted Personal Interview
When performing a computer-assisted personal interview (CAPI), the interviewer takes a laptop computer to the interview and codes the data into the computer as it is provided. This technique allows;
- more flexibility to move around the form and skip questions
- some edit checks to be carried out at the time of the interview, thus improving data quality, and
- (because of the above reasons) the overall timeliness of the survey is improved.
Respondents can also sometimes take the survey more seriously because a computer is involved. However, the method does have several drawbacks: there is an increased cost in set-up, maintenance of the computer equipment and training of interviewers in the use of CAPI, and the actual interview time increases as responses are coded and edited at the time of the interview.
In the ABS self-enumeration methods are mostly used in surveys of businesses. Self-enumeration surveys are those in which it is left to the respondents to complete the survey questionnaires. The following are three of the most common self-enumeration methods.
Questionnaires are mailed out to respondents with a return-paid envelope so that the respondent can mail back the completed form. This technique allows:
- the respondent is able to complete the questionnaire in their own time and not all in one session,
- the respondent can then check records and with other people,
- more detailed instructions and explanations can be included for better quality data,
- wider geographic areas can be covered for far lower cost than personal interviews,
- allows access to 'difficult-to-contact' respondents (those people who only provide post office boxes as addresses or are away from home a great deal).
The major disadvantages with postal surveys is that they can have a lower response rate, due in part to the difficulty in maintaining accurate address and contact details. The reliance on postal services and respondents completing questionnaires can cause data to be slow to become available due to the lag in time between when the questionnaire is mailed out and the time the questionnaire is returned, although this effect is reduced when surveys are repeated regularly. There is also a limit on the complexity of the questionnaire to avoid confusion or errors, compared to interviewers trained in questionnaire use. This method is not appropriate for potential respondents with limited ability to read or write English unless questionnaires are provided in the appropriate language.
Dropoff-Mailback and Dropoff-Pickup
These two closely-related methods of self-enumeration surveys both provide higher response rates than postal surveys. In both cases, the questionnaire is delivered to respondents by an interviewer who explains the aims of the survey and how to fill out the questionnaire. The questionnaire is left with the respondent to be completed and either mailed back by the respondent or picked up by the interviewer at a later date. The costs involved in using interviewers makes this technique more expensive than postal surveys, but usually less expensive than personal interviews. This method has the same disadvantage as personal interviewing in that the respondent has to be available when the interviewer visits.
Electronic Form or CASI
An electronic form (eform) is an electronic version of the questionnaire that can be sent to the respondent's computer via email or accessed from the World Wide Web. The data entered onto an eform can be edited as it is entered, thus improving data quality. The use of electronic returns also produces a faster response than other self-enumeration methods. Questions can also be sequenced so that only the questions relevant to the respondent are visible. The disadvantages are: increased cost for development of the forms, maintenance of the related systems and security, and the absence of well-established design standards. Also, this technique requires respondents to have compatible computer software and help-desk type staff can be necessary to support the use of the form. Electronic forms on disk or CD are also sometimes used in mail-out or drop-off surveys instead of a paper form.
In the ABS telephone surveys are used for both household and business surveys to some extent, however telephone data collection methods are used more widely for intensive follow-up and post-enumeration tests. Telephone interviews involve potential respondents being telephoned and asked the survey questions over the phone. This technique:
- reduces costs, compared to personal interviews, as fewer interviewers are needed and there are no travel costs involved,
- produces more timely results, and
- call-backs for people 'not-answering' and follow-ups for additional information are relatively quick and inexpensive.
However, telephone interviews are very limited in the number and complexity of the questions that can be asked and, because of the ease with which the respondent can terminate the interview, non-response and partial non-response can be high. A bias is also introduced because people with no phones or who are rarely available are excluded and it is difficult to produce a reliable sampling frame because of unlisted numbers and changes in addresses (therefore changes in numbers). There are also problems with convincing respondents of the authority behind the survey and the confidentiality of results.
Computer-Assisted Telephone Interview
Computer assisted data collection methods can also be used in telephone surveys. Computer Assisted Telephone Interviewing (CATI) involves responses being keyed directly into a computer by the telephone interviewer. This technique allows for:
- some editing to be carried out immediately (which improves the data quality and decreases processing time),
- 'call scheduling' to take place. Respondents can be called at convenient times or when data is available. Also, if the phone is engaged, the system will reschedule the call, and
- questions to be sequenced so that only relevant questions are visible to the interviewer (therefore reducing interviewer errors).
- monitoring of interviewing staff so that consistency of performance is higher.
However, CATI is expensive to implement and maintain with extensive training needed for interviewers to perform properly. Interview time is also increased because editing is done whilst the interview is being performed and this can cause increased non-response.