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According to Lachin and Bailar, almost half of the
epidemiological studies conducted are of the cross-sectional design. This does not include
randomized, controlled clinical trials, which are classified as experimental, rather than
observational studies. The frequency of the study designs used reflects the cost of
conducting research. Cross-sectional are more economical than cohort studies to conduct.
The least expensive are case-controls. The problem with case-controls is selecting the
appropriate controls. |
