For PCA and FA, missing data pose serious problems.
Missing data on tumour stage poses as a serious problem in the evaluation of early detection programmes.
To assess the risk posed by missing data (MD) to the power and validity of trials evaluating palliative interventions.
To address the limitations posed by missing data we performed our primary analysis in the complete case data.
Despite the serious threat posed by missing data, there are several fairly easy solutions to the problem.
As excluded women were not different from participating women with respect to BMI, our main exposure of interest, or screening participation, our outcome, missing data were not likely to pose major bias in our results on association between BMI and screening participation.
In the present analysis, the increasing levels of missing data with increasing follow-up time pose some limitation.
Unequal sample size at each level does not pose a problem for HLM, and missing data is also tolerated.
In general, prospective recruitment methods are considered to be preferable, whereas retrospective recruitment poses some methodological problems regarding data quality and missing data.
