In order to get valid conclusions from clinical research including surgical research, rational and considerate design before starting the research and proper statistical analysis after collecting data cannot be over emphasized. Wee-designed
research
protocols should include precise and clear study objectives, patient inclusion and exclusion criteria, treatment schedule, control selection, outcome evaluation criteria, data collection and database construction methods, statistical analysis
scheme,
and informed consent. Available study designs for surgical research consists of two different types: one is observational study including case report, case series study, cross-sectional study, case-control study, and cohort study, and the other
is
experimental study such as randomized controlled clinical trials. Researchers have to know the pros and cons of each design and interpret study results with caution. When planning an experimental study, ethical problems should be considered first
and
then scientific methods to get a valid conclusion should be established, which should include at least statistical sample size determination, maximum comparability between study groups, random allocation scheme of study subjects, using blind
technique
for collecting objective and correct information, complete follow-up of the patients, reliable and objective outcome criteria, and proper selection of statistical analysis. Th author wants to introduce basic concept of statistical terms and the
need for
understanding study designs and statistical analysis in clinical research. Common and typical statistical analysis procedures are demonstrated with hypothetical examples using continuous and nominal data.
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