1. How to Read Scientific Journal Articles

2. Major article sections
Abstract -- brief summary of entire article
Introduction -- includes literature review; states why the research is relevant.
Methods -- identifies how patients were selected, what study procedures entailed, and statistical methods used.
Results -- presents objective results
Discussion -- interprets results; states study strengths/weaknesses; identifies future work

3. What population(s)?
The study eligibility criteria define the characteristics of the patients studied, and therefore the population(s) to which the results can be extended.
The baseline characteristics define the characteristics of the patients studied, and therefore the population(s) to which the results can be extended. (Often, Table I.)

4. Identification of groups
Typically, one group is considered a control group, while other groups are considered new treatment groups.
The groups should be similar, on average, except with respect to the primary treatment(s) of interest. (Often, Table I.)
Ideally, groups will be created by randomly assigning individuals to groups.

5. With respect to what are the groups being compared?
The main variables by which the groups are compared are called the primary outcome measures.
A good study is designed with the primary outcome measures in mind.
The less important variables by which the groups are compared are called the secondary outcome measures.

6. How are outcome measures be analyzed statistically?
The type of data and how the study was designed determine the appropriate analysis methods.
Categorical (binary) data are often summarized as percentages, but also odds ratios and relative risks.
Numerical (measurement) data are often summarized as means, but also medians.

7. Presentation of results
Statistical results can be presented in words or in a table.
If a summary measure, like a percentage or a mean, is reported without a P-value or a confidence interval, the result only applies to the sample of patients in the study.

8. Presentation of P-values
In a table, P-values are usually indicated by a footnote.
In writing, P-values are usually indicated in parentheses after the conclusion of a hypothesis test is stated.
It is the reader’s job to infer the null and alternative hypotheses of the hypothesis test.

9. Presentation of confidence intervals
Confidence intervals for a mean are typically presented in one of three ways.
Sample mean ± SD, (“standard deviation”)
Sample mean ± SE (“standard error”)
The lower and upper limits of the interval
If “Sample mean ± SD”, the 95% margin of error is 2×(SD÷sqrt(n))
If “Sample mean ± SE”, the 95% margin of error is 2×SE.

10. Presentation of confidence intervals
It is the reader’s job to know what value is relevant to the confidence interval:
If a confidence interval for a difference in two means or a confidence interval for a difference in two proportions, then is 0 in the interval?
If a confidence interval for a relative risk, or a confidence interval for an odds ratio, then is 1 in the interval?
And so on ...

11. Evaluation of the strengths/weaknesses of the study
Is there a control group?
Is the study a randomized experiment or an observational study?
Were the patients selected and assigned to their treatments in an unbiased manner?
Were the patients and physicians blinded to treatment assignment?

12. Evaluation of the strengths/weaknesses of the study
Was the sample large enough to get useful statistical results?
If the sample was really large, were confidence intervals created to show that a rejection of the null hypothesis is actually meaningful?
Are the conclusions of the study overstated?
Do the authors point out future necessary research?