5. Step 2: Appraise the quality of the study

5.1. What about statistics?

5.1 What about statistics?

You do not need to check, or be familiar with, every statistical procedure. 

However, being aware of the key issues relevant to each specific study design is helpful.

Statistical significance doesn’t necessarily equal biological significance.

Even if some issues around statistics are unclear, you will get a good impression of the overall quality of the paper after assessment of the other quality criteria. Most research in this field has shown that the major flaws are usually related to study design and reporting, rather than statistics.

You do not need to be a research scientist or a statistician to appraise the literature!

Statistics top tips

  • Are details of statistical methods included?
  • Look for a sample size calculation in the methods section. This should state how many animals will need to be studied in order to observe a statistical difference. More animals will be required if the difference between groups being studied is expected to be small.
  • The probability value (p-value) can be set at any level, but standard practice is to use 0.05 as the level for significance. The p-value indicates whether an outcome is likely to be real or just due to chance. In this case, a p<0.05 suggests the finding is likely to be real.
  • In the results section, does the author use the correct number of animals and the same p-value for significance that were outlined in the methods section?