Pub. date: 2008 | Online Pub. Date: November 27, 2007 | DOI: 10.4135/9781412953948 | Print ISBN: 9781412928168 | Online ISBN: 9781412953948| Publisher:SAGE Publications, Inc.About this encyclopedia
Jane K. Burke-Miller
Intent-to-treat analysis (ITT) requires that all study subjects be included in outcome analyses in the study condition in which they were assigned, or were intended to be treated, regardless of actual treatment or adherence to the research protocol. After being assigned to a study condition, subjects may not actually use the treatment or intervention, may use less than intended doses, may drop out from the research program and therefore have indeterminate outcomes, or may even cross over between study conditions. These subjects may differ systematically from those who follow the protocol, and their removal can invalidate random assignment, introduce bias, and lead to inappropriate interpretation of statistical tests. The concept of ITT originated in pharmaceutical and randomized clinical trials but applies to behavioral interventions as well. ITT is associated with effectiveness trials, which try to emulate real-world circumstances ...