Infographic: Sample size, effect size, and statistical power: A guide


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 Sample size, effect size, and statistical power: A guide

Ever wondered how many participants you need to ensure your findings are solid? How likely is it that the relationship you’ve detected actually exists and isn’t due to chance? Excited to learn how to go beyond p values in hypothesis testing? Look no further! The infographic below demystifies sample size, statistical power, and effect size for biomedical researchers, breaking down these concepts into bite-sized nuggets so that you can design studies that stand up to scrutiny and make a real impact.

An infographic explaining Sample Size, Effect Size, and Statistical Power for Biomedical Researchers Sample Size • Sample size refers to the number of individuals or data points you include in your research study. • It directly affects the reliability of your findings. Statistical Power • Statistical power is the likelihood of detecting a true relationship, effect, or difference if it exists in your data. • You need adequate power if you want to avoid false-positive and false-negative errors. Effect Size • Effect size tells you whether the differences or relationships that you detect are meaningful in real life. • Larger sample sizes are needed to detect smaller effects accurately. • Biomedical researchers often focus on numerically small differences (e.g., normal vs prediabetes HbA1c levels), so sample size calculations are crucial. Benefits of an Adequate Sample and Statistical Power Representativeness: • A larger sample size can better represent the diversity within the population you're studying. • This reduces the chance of drawing incorrect conclusions based on a biased sample. Precision and Confidence: • A larger sample size leads to more precise estimates and narrower confidence intervals. • This means you can have more confidence in the accuracy of your results. Efficient Use of Resources: • Adequate power means that your findings are likely to be high-quality. • You don’t waste resources on an underpowered study that yields unreliable results. • You don’t waste resources on an unnecessarily large sample size, inconveniencing participants.

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