Previously in this series I have given an overview of the main types of study design ... fully ecological studies, their uses, advantages and limitations. An ecological study is an observational ...

These particular groups of non-users are generally not included in RCTs, and should also be avoided in observational studies. The active-comparator design has three main advantages: increased ...

We then compared the results of the original reports according to the type of research design. For the five clinical topics and 99 reports evaluated, the average results of the observational ...