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sampling procedures described? Make some notes and then turn to the discussion in Section 6. Data collection methods Quantitative and qualitative researchers also tend to utilize different data collection methods to pursue their aims. Quantitative methods are designed to promote standardization and control, whereas qualitative methods aim for a balance between flexibility and consistency (15). Quantitative data collection methods Data collection techniques (such as tests) and devices (such as questionnaires and interview schedules) are sometimes known as instruments. The most commonly used instruments in the collection of quantitative data are: • tests and measurements (often used in experimental studies); • questionnaires and structured interview schedules (often used in surveys); and • structured observation schedules. In well designed quantitative studies, data are recorded in tightly structured formats, which may be in the form of questionnaires or interview/observation schedules. In the case of questionnaires, data forms are completed by research participants (sometimes known as respondents), while in other cases the researchers complete the forms. It is good practice to include a copy of the survey questionnaire, observation schedule or other data form in the research document although, in the case of research articles, the need for brevity may prevent this. Inclusion of the data form may aid comprehension of the research document and will allow readers to evaluate the quality of data collection procedures and the validity and reliability of the study (see the section on rigour, page 42). Experiments and quasi-experiments may involve the collection of several different types of data. For example, data collected during a clinical drug trial might include objective biophysiological measurements such as blood pressure levels and body weight, patients’ subjective reports of their symptoms, and the presence or absence of any confounding variables such as other medication taken. Patients may be weighed and have their blood pressure taken each time they visit the person managing the trial. They may record their symptoms daily on a structured diary card (using, for example, the terms “mild”, “moderate” or “severe” to describe pain), which they hand in at each visit. They may be verbally questioned about their use of other Reading and evaluating research reports page 25 medication, concurrent illness and other potentially confounding variables. In other words, the data collected during the course of a clinical trial may involve biophysiological measurement, questionnaire and interview techniques. Data will be recorded on a data form at each visit. In a quasi-experiment designed to assess the effect of an educational package, data on nurses’ knowledge may be collected pre- and post-test using questionnaires or structured interviews. When critiquing experimental and quasi-experimental data collection techniques, you should attempt to assess whether data have been collected on potentially confounding variables. It is also important to consider ethical issues (discussed on page 40). This may be particularly relevant where biophysiological measurements are concerned, as some tests may be painful, distressing or even dangerous. Exercise 10 What research instruments were used in the study described by Allen et al.? Are copies of these included in the article? Turn to Section 6 for discussion. Questionnaires may be distributed to a survey sample by post or, for smaller studies, by hand. In either case, attempts should be made to preserve respondents’ anonymity. Individual questionnaires are usually identified by a code number rather than a name and, even where distribution has been by hand, questionnaires are often returned in a prepaid envelope. Questionnaires should be designed with a high proportion of closed (“yes/no” or “tick box”) rather than open (“give details below”) questions. Questions should be arranged in a logical order and should avoid complexity and ambiguity. Pilot work (as discussed above) can help researchers to identify and eliminate questionnaire design flaws. Structured interviews are similar to questionnaire surveys, except that researchers (sometimes called “data collectors”) obtain the data from participants by reading questions from and recording answers on an interview schedule. This can be done face-to-face or over the telephone. To preserve a degree of anonymity, completed schedules usually bear a code number rather than a name. The issues involved in designing an interview schedule are very similar to those involved in questionnaire design. Although data collectors are able to clarify questions that participants do not understand, they must be careful that they do not bias the data when doing so. Each participant should be asked the questions in a standardized way. This is extremely difficult to achieve in practice, particularly when there are two or more data collectors. Training may help to minimize some of these problems. Some research topics might be better dealt with by questionnaire, some by telephone and some face-to-face. For example, people might be willing to complete a questionnaire about a potentially embarrassing subject, such as incontinence or impotence, but might not wish to talk about it. As factors such as this may affect the
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