Chapter 5 measurement concepts: reliability the consistency or stability of a measure. Item-total correlations correlations of each item score with the total score based on all items: low-correlation items are actually measuring a different variable and can be eliminated. Interval scale are numeric scales in which the intervals between numbers on the scale are equal in size: ratio scale have an absolute zero point that indicates the absence of the variable being measured. Expresses data in nonnumerical terms and bases conclusions on interpretations drawn by the investigators: naturalistic observation a descriptive method in which observations are made in a natural social setting. Researchers study people in social and organizational settings or animals in their natural habitats: field observation, participant observation occurs when a researcher takes an active, insider role in what he or she is studying. This can yield data not available to nonparticipants observers. Limits of naturalistic observation most useful when investigating complex social settings.