The COSI Model

We use the COSI model (Bidwell and Jensen, 2004) to guide the search process. It outlines three types of literature searches:

 The COre search - This search uses essential sources only - focusing on the greatest expected yield - and uses mostly published and indexed literature

 The Standard search - This search includes additional sources which are expected to add to the Core search, including the practice literature

 The Ideal search - This search attempts to "leave no stone unturned"

This model highlights a key point about literature searching, that finding most or all of papers for a given topic or question is based on the time spent searching. However, we can also search in a targeted way, in places we expect to find some or a few of the main papers on a given topic or question. In other words, the three types of searches in the COSI model can be “ranked in the order of expected yield (in terms of return for time spent)” (Bidwell and Jensen, 2004).

In sum, there is a trade-off between the ideal search for finding the relevant literature and the time frame given. To determine which type of search is right for you or your situation, you must go back to your original research aim or question.

Reference:
Bidwell S, Jensen MF. (2004) Chapter 3: Using a Search Protocol to Identify Sources of Information: the COSI Model in Topfer L-A, Auston I (Eds). Etext on Health Technology Assessment (HTA) Information Resources. Bethesda, MD: National Information Center on Health Services Research and Health Care Technology (NICHSR), US National Library of Medicine.