How would you characterize your familiarity with the inter-class correlation coefficient (ICC) within the context of exposure biomarkers?

Answer Explanations

• Not very familiar

  Expert 9
  Although it sounds like a very useful concept.  I am more familiar with the broader concept of between- and within-person variance.
• Somewhat familiar

  Expert 3
   I regularly use the ICC in my exposure assessments, but I am often constrained by the limited amount of data I receive from colleagues, as they often do not repeat measurements on the same person. 
• Very familiar

  Expert 4
  Similar to the response above. 
• Very familiar

  Expert 6
  See my response to 1.3 above.  I think this paper would benefit from a discussion (even if brief) of the need for repeat measurements of study outcome, especially for those health outcomes known to vary within individuals, such a blood pressure, pulse, and hormone levels.
• Somewhat familiar

  Expert 7
   A higher ICC indicates that a larger proportion of the total variability is due to between-person differences, meaning the biomarker measurements are more consistent within the same individual across different time points.  a desirable biomarker will have high ICC>
• Somewhat familiar

  Expert 1
  The use of the ICC to assess the variability is an important tool in biomonitoring. However, new methods are being developed to assess longitudinal studies with repeated measurements. Obviously, the inclusion of other individual factors such as age, gender, ethnicity, body mass index and any pathologies that may affect the biomarker of interest are important.   
• Somewhat familiar

  Expert 8
  Used this in my studies + in my courses on exposure assessment 
• Very familiar

  Expert 5
  Very familiar - I've conducted field research, taught and published in this area.
• Very familiar

  Expert 2
  As an experienced biostatistician, I am very familiar with the intraclass correlation coefficient (ICC) within the context of exposure biomarkers due to its crucial role in quantifying the proportion of total variability in biomarker levels that can be attributed to between-person differences, as opposed to within-person variability. The ICC is a key metric in exposure assessment studies, particularly those involving repeated measures or clustered data, as it helps in understanding the reliability of biomarkers over time and the consistency of exposure levels within individuals.
   In my work, I have frequently utilized the ICC to evaluate the degree of variability and to guide the design and analysis of studies, ensuring that both within- and between-person variability are appropriately accounted for in statistical models. For example, in longitudinal studies where repeated measurements are taken from the same individuals, and in studies aimed at distinguishing between persistent and transient exposure levels, I have applied and interpreted the ICC to accurately assess exposure, reduce measurement error, and improve the precision of epidemiological findings.