unobtrusive measures

Techniques for collecting data without the knowledge of respondents. Two types-the covert and the indirect-may be identified. The former include, for example, covert participant observation , undisclosed notetaking, or use of one-way mirrors. The latter involves the use of personal documents and other records which might offer indirect measures of variables such that the need for interaction between the investigator and his or her subjects is obviated. (For example, student satisfaction with new educational practices might be assessed by inspecting records of attendance at classes and rates of switching between course, rather than direct interview or questionnaire.) The justification of such methods is that, because respondents are unaware of their status as research subjects, their activities are unaffected by certain potential biases in the research situation itself-such as the desire to please the investigator. Although some of these techniques (most notably covert observation) are now frowned upon by professional sociological associations as being ethically suspect, the imaginative use of existing documentary sources for novel research purposes is occasionally very effective, although one is normally working ‘against the grain’ of the data since they have usually been collected for purposes other than those embodied in the research. See also interview bias ; research ethics.