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What Is Sample Size Calculation?

Sample size calculation determines the number of subjects required for a clinical study – a key parameter for sound statistics and reliable results.

Too large a sample size drives up costs, resource use, and time; too small a sample size leads to inaccurate estimates and unmet acceptance criteria. This may require additional recruitment or even the repetition of entire studies, or parts thereof.

Key Considerations for Sample Size Calculations

While excessively large sample sizes unnecessarily drive up the effort and cost of conducting a clinical study, insufficient sample sizes lead to inaccurate estimates and results that lack statistical robustness – meaning hypotheses cannot be confirmed, or acceptance criteria are not met. In the worst case, studies or parts thereof must be repeated, which is time-consuming and costly.

Where no specific regulatory requirements apply, sample size planning is based on statistical calculations. This requires assumptions about test performance (e.g. sensitivity and specificity) and acceptance criteria, as well as additional parameters drawn from literature or preliminary studies. Conservative assumptions are advisable – representing the worst-case scenario that still meets acceptance criteria.

TRIGA-S supports sample size calculation for both clinical performance studies (IVDR, ISO 20916) and pharmaceutical clinical trials. Using realistic, conservative assumptions and scenario analyses, we actively reduce the risk of under- or over-planning and ensure efficient use of resources.

Need support determining sample sizes for your clinical studies? Get in touch.

Contact us now

Veronika Lay, Senior Manager Biostatistics / Data Management

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IVDR: In Vitro Diagnostic Regulation

ISO: International Organization for Standardization

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