The Campbell method can be expressed in three fundemental parts:


► The method behind a Campbell systematic review consists of four steps:
    
        1. Make criteria for scientific character of included studies.
        2. Make a systematic search for studies by means of a standardized 
            search-strategy.
        3. Value all studies found in the search according to the criteria made.
        4. Analyse those studies which meet the inclusion criteria.


► All methods used, criteria and choices made in the systematic review have to be documented and publiced. This is to contain transparency.


► All work need to be approved by the independent, international network for research, The Campbell Collaboration.


A main justification for the Campbell effort is the volume of studies purporting to show that certain interventions “work”. Often, multiple studies of the same intervention exist, many of which are based on anecdotal or other fragmentary evidence. Reports from such studies can influence decisions about whether to adopt an intervention. Frequently, interventions do not actually have the effects they are purported to have, so decisions to adopt programs may be made based on faulty or incorrect evidence.