Addi van Bergen

Supplementary material chapter 2 165 Is it worth continuing? 3. Was the exposure accurately measured to Yes Can’t tell No minimise bias? HINT: Look for measurement or classification bias: • Did they use subjective or objective measurements? • Do the measurements truly reflect what you want them to (have they been validated)? • Were all the subjects classified into exposure groups using the same procedure 4. Was the outcome accurately measured to Yes Can’t tell No minimise bias? HINT: Look for measurement or classification bias: • Did they use subjective or objective measurements? • Do the measures truly reflect what you want them to (have they been validated)? • Has a reliable system been established for detecting all the cases (for measuring disease occurrence)? • Were the measurement methods similar in the different groups? • Were the subjects and/or the outcome assessor blinded to exposure (does this matter)? 5. (a) Have the authors identified all important Yes Can’t tell No confounding factors? List the ones you think might be important, that the author missed. (b) Have they taken account of the confounding Yes Can’t tell No factors in the design and/or analysis? HINT: Look for restriction in design, and techniques e.g. modelling, stratified-, regression-, or sensitivity analysis to correct, control or adjust for confounding factors 6. (a) Was the follow up of subjects complete enough? Yes Can’t tell No (b) Was the follow up of subjects long enough? Yes Can’t tell No HINT: Consider • T he good or bad effects should have had long enough to reveal themselves