Most common in survey research and other quantitative methods. Often used in quantitative research because: difficult to devise a single measure of complex concepts. Especially true with regard to attitudes and orientations. Researchers devise several items, each providing some indication of the variable. A single indicator provides a valid and reliable measure of some variables. Other variables are more difficult and complex to measure: e. g. Marital status, number of children: some may require > 1 indicator of a variable, some may involve a # of dimensions that calls for multiple indicators, some may be concerned with degree to which a variable is present. Way scores are assigned in each: index- accumulate scores assigned to individual attributes, scale- assign scores to pattern of responses. Uses differences in intensity among the attributes of the same variables to identify distinct pattern of response. Some items reflect a relatively weak degree of the variable while other reflect something stronger.