Abstract
This paper describes a range of models and methods for synthesizing diverse forms of research evidence. Although this topic is applicable to many contexts (e.g. education, health care), the focus here is on the research traditions of distance education and online learning. Thirteen models and methods are described, and seven examples from distance education and online learning are used to illustrate them. The models are classified as systematic, purposeful, and mixed and are described and compared in terms of purpose, methodological aspects, and expected outcomes.