Statistical power is the likelihood that a statistical test will:
Power can range between 0 and 1, with higher values indicating a greater likelihood of detecting an effect.
What is statistical power?[edit | edit source]
Statistical power is the probability of correctly rejecting a false H0 (i.e., getting a significant result when there is a real difference in the population).
Desirable power[edit | edit source]
- Power ≥ .80 generally considered desirable
- Power ≥ .60 is typical of studies published in major psychology journals
Increasing power[edit | edit source]
Power will be higher when the:
Estimating power[edit | edit source]
Statistical power can be calculated prospectively and retrospectively.
If possible, calculate expected power before conducting a study, based on:
- Estimated N,
- Critical α,
- Expected or minimum ES (e.g., from related research)
Report actual power in the results.
Power calculators[edit | edit source]
Try searching using terms such as "statistical power calculator" and maybe also the type of test, and you should turn up links to useful pages such as:
- Statistical power calculators
- One Sample Test Using Average Values
- Post-hoc Statistical Power Calculator for Multiple Regression
References[edit | edit source]
- Cohen, J. (1992). Power primer. Psychological Bulletin, 112, 155-159.