Finally, as a future study, we may develop an efficient simulation procedure that can analyze comprehensively the impacts of relative variability in the group means, subject-specific exposure variation, and measurement error variance.
The residual ejk reflects within-state variation among counties, including measurement error and variation that is not explained by the model.
Much of this variation is attributable to either measurement error or variation in TL between cells in the same individual.
Heterogeneity, ranging from measurement error to variation among individuals or regions, influences all levels of data collected for risk assessment.
Whilst it is possible (in theory) to reduce measurement error, physiological variation is inherent, and can cause difficulty in attempts to characterise disease or to monitor the effects of therapy.
sCD40L was significantly associated with UFPs at lag 0, but its association with PM2.5 started to be significant from lag 3 to 4. The difference in biomarker responses to UFPs verses to PM2.5 may reflect the inherent differences in underlying biology, measurement error, sampling variation, or the confounding effects of the other correlated pollutants.
Hankins [ 22] has proposed that negatively worded items introduce additional variance to the model above that created through random measurement error and variations in the measured construct and that this perhaps results from an ambiguous response frame for these items.
Single-site time-series studies have been criticized because of exposure measurement errors, substantial variation of the air pollution effects and the heterogeneity of the statistical approaches used in different studies [ 13].
Total variation comprises the within- and between-subject variation, with the former further subdivided into analytic variation, arising from measurement error and true biological variation.
