Measurement and Size

A lab equipment item. Courtesy: National Institute of General Medical Sciences

• assist in determining whether a health condition exists   
• provide information about exposure to and existence of infection, or
• confirm behaviors 

Determining which of these are important to the research question is the first step. At the same time, the researcher must determine whether there is an assessment available and whether it is ethical to make such an assessment. Consulting with an expert about the latest biomarker assessments on the pertinent topic and getting recommendations about possible laboratory collaborations is critical before including collection of biomarkers in population research.

Sample Size Considerations

As with other exposures of interest, the prevalence of a particular disease state or health condition will need to be considered when determining the number of participants to be recruited. Similarly, if the study is examining the occurrence of incident cases over a specified time period, the minimum sample size to measure change will have to be considered. Involving a statistician in determining minimum sample sizes will be important when biomarkers are collected because of the costs associated with this addition to the protocol.