All are true about Coho studies EXCEPT: September 2012

Ans: B i.e. Useful for rare diseases Case control studies Advantages Good for studying rare conditions or diseases Less time needed to conduct the study because the condition or disease has already occurred Lets you simultaneously look at multiple risk factors Useful as initial studies to establish an association Can answer questions that could not be answered through other study design Disadvantage Retrospective studies have more problems with data quality because they rely on memory and people with a condition will be more motivated to recall risk factors (also called recall bias). Not good for evaluating diagnostic tests because it's already clear that the cases have the condition and the controls do not It can be difficult to find a suitable control group Coho studies Advantages Subjects in cohos can be matched, which limits the influence of confounding variables Standardization of criteria/outcome is possible Easier and cheaper than a randomized controlled trial (RCT) Disadvantages Cohos can be difficult to identify due to confounding variables No randomization, which means that imbalances in patient characteristics could exist Blinding/masking is difficult Outcome of interest could take time to occur