A. When should measurement error bias/sensitivity analyses be conducted? |
1. When assessment of the observed diet-disease associations was estimated using a crude instrument of dietary intake such as a FFQ. |
2. Essential when the study report aims to translate their findings into policy decision-making actions for a variety of stakeholders. |
B. How does one select a method to conduct a model measurement error bias/sensitivity analysis? |
1. Aim to balance realistic modelling with practicality of conducting the modelling (e.g. availability of software). |
2. Report the measurement error bias/sensitivity analyses as transparently as possible, giving clear details of what was done and the assumptions made. |
3. Make the statistical analysis code used to conduct these measurement error bias/sensitivity analyses available either as supplementary web material or by publishing it as an appendix to the main report. |
C. How does one assign values to the parameters of the model? |
1. Assign values based on the latest information from available data such as internal calibration sub-studies or external calibration studies with a similar design. |
2. Choose a range of plausible values in order to assess the impact on the overall findings of a range of scenarios. |
3. Evaluate the impact of departures from the assumptions of the classical measurement error model (such as correlated errors between the dietary instruments used or non-differential measurement error). |
D. How does one present and interpret the measurement error bias/sensitivity analysis? |
1. Present the results in the form of a table or figure where it is possible for the reader to see the complete set of analyses performed. |
2. Quantify the direction of the bias based on departures from the classical measurement error model on the overall study findings (e.g. are the observed diet-disease associations likely to be over- estimated or under-estimated?). |
3. Describe the implications in light of the measurement error bias/sensitivity analysis (are the policy decisions changed or toned-down in light of these findings?). |