Other issues in making trials effective

The clinical trial protocol is a detailed written plan that outlines how the study procedures are to be carried out and how the data are to be collected and analyzed. It insures the quality and integrity of the trial, particularly when multiple research sites are participating in data collection (Chow and Liu, 1998). The purposes of the protocol are to outline  

Inclusion and exclusion criteria are used to define eligibility parameters for study participation. These criteria are established to insure that the study 

Examples of parameters used to define inclusion and exclusion criteria often include  

While clearly outlined criteria are essential, a lengthy list of exclusions can also impede subject recruitment. Therefore, a balance must be struck between what is scientifically desirable and that which is still practical with regard to the number of study sites and length of time required to complete the trial. 

The number of study sites to be used for a clinical trial depends on the characteristics and number of subjects that need to be recruited. Often, a sufficient number of participants cannot be enrolled from a single site, especially if the study inclusion criteria are restrictive and the timeframe for recruitment is limited. In order to complete the study within a reasonable period of time, an inclusion of multiple research centers is often necessary (Chow and Liu, 1998). The selection of study sites depends on several factors including  

---