We develop here a reliability coefficient applicable to a largely neglected component of data-generating processes: the identification of units for analysis within essentially continuous phenomena. Whether we count evidence found in texts, examine relevant sections of videotapes, or punctuate interaction sequences suitable for further analysis, unitizing underlies all quantifications. Measures of the reliability of this process provide researchers with information regarding the degree to which data may be trusted. In compliance with widely used reliability standards, we conceive the new measure as a member of a family of reliability coefficients alpha--which have so far been applicable only to various coding tasks--and derive it accordingly.

* The Annenberg School of Communication, University of Pennsylvania