Dan Mayer Essential Evidence-based Medicine

The medical literature: an overview 29
Methods
The methods section is the most important part of a research study and should
be the first part of a study that you read. Unfortunately, in practice, it is often
the least frequently read. It includes a detailed description of the research
design, the population sample, the process of the research, and the statistical
methods. There should be enough details to allow anyone reading the study to
replicate the experiment. Careful reading of this section will suggest potential
biases and threats to the validity of the study.
(1) The sample is the population being studied. It should also be the population
to which the study is intended to pertain. The processes of sample selection
and/or assignment must be adequately described. This includes the eligibility
requirements or inclusion criteria (who could be entered into the
experiment) and exclusion criteria (who is not allowed to be in the study
and why). It also includes a description of the setting in which the study
is being done. The site of research such as a community outpatient clinic,
specialty practice, hospital, or others may influence the types of patients
enrolled in the study thus these settings should be stated in the methods
section.
(2) The procedure describes both the experimental processes and the outcome
measures. It includes data acquisition, randomization, and blinding conditions.
Randomization refers to how the research subjects were allocated
to different groups. The blinding information should include whether the
treating professionals, observers, or participants were aware of the nature
of the study and if the study is single-, double-, or triple-blinded. All of
the important outcome measures should be examined and the process by
which they are measured and the quality of these measures should all
be explicitly described. These are known as the instruments and measurements
of a study. In studies that depend on patient record review,
the process by which that review was carried out should be explicitly
described.
(3) The statistical analysis section includes types of data such as nominal,
ordinal, interval, ratio, continuous, or dichotomous data; how the data are
described, including the measures of central tendency and dispersion of
data; and what analytic statistical tests will be used to assess statistical relationships
between two or more variables. It should also note the levels of α
and β error and the power.
Results
The results section should summarize all the data pertinent to the purpose
of the study. It should also give an explanation of the statistical significance
of the data. This part of the article is not a place for commentary or