unobtrusive or nonreactive measures

Unobtrusive measures are measures that do not involve directly asking people their opinions concerning a certain topic. They are used in research to measure behavior indirectly or to reveal underlying motives and values. Examples of unobtrusive measures include naturalistic observation and content analysis. Nonreactive measures are measures of data or information that are collected without any change or alteration to the behavior being studied. They provide researchers with objective data that cannot be influenced by any outside factors. Examples of nonreactive measures are archival studies, physical records, population statistics, and census data.