Studies can generally be classified in one of two ways: observational or experimental.
Observational studies are those in which investigators observe subjects, classifying them based on levels of one (or more) explanatory variable(s) and a response of interest. Observational studies generally fall in one of three classes.
The three main classes are case/control, cohort and cross–sectional studies.
Experimental studies may be thought of studies where a research makes an intervention (such as giving a particular drug treatment to a patient). Then, the subjects are followed over time, and the response of interest is measured.
Experimental studies may be thought of studies where a research makes an intervention (such as giving a particular drug treatment to a patient). Then, the subjects are followed over time, and the response of interest is measured.
Experimental studies will be focused with historic controls and randomized clinical trials.
The usefulness in terms of determining causation varies significantly among these types of studies. Randomized clinical trials are considered the best in this sense. Case–control studies are probably the weakest in that sense. However, the quality with which the data are collected can be just as important as the study design (Hill, 1953).
The usefulness in terms of determining causation varies significantly among these types of studies. Randomized clinical trials are considered the best in this sense. Case–control studies are probably the weakest in that sense. However, the quality with which the data are collected can be just as important as the study design (Hill, 1953).
The named studies will be discussed in upcoming posts.
:) Biostatistics! I think a friend of mine at Shiraz University studies Biostatistics for her Master. I will try to introduce you as she will be able to help you on learning more on this subject. By the way I will leave Iran in next month and I will send you more information form Australia.
:)