Occasional observations of negative diameter change were assumed to result from unbiased measurement errors, therefore these negative diameter changes were kept to avoid introducing bias.
In extreme cases, measurement error could therefore be speculated to become even twice as high as in typical lab experiments.
The SDD, derived from the SEM, represents measurement error and, therefore, the threshold that must be overcome to ensure real change.
Further, the high coefficient of variation at lower values of 25(OH D suggests that there may be measurement error and therefore exposure misclassification of 25(OH D.
This may have resulted in larger measurement errors and therefore lowered power of statistical tests.
We further suspect that some extreme waiting times were due to measurement errors and therefore set maximum waiting time to four and a half years (1650 days).
In reality this assumption is unlikely to hold perfectly, and measurement errors may therefore have resulted in some bias towards the null for single pollutant models, or in either direction for multi-pollutant models.
[11], since X is observed with measurement error, Y is therefore not missing at random if no further assumptions are made.
In combination with the self-reported nature of our height, weight and physical activity data, this is likely to have introduced some measurement error and may therefore have attenuated our estimates of the effect sizes.
Taken together, this and other recent studies suggest that with more sensitive assays, blips in excess of 200 copies/mL are increasingly likely to be due to non-adherence, rather than due to either random variation in residual viremia or assay measurement error, and are therefore a reason for clinicians to discuss adherence with their patients.
