New guidance to improve sample size calculations for trials: eliciting the target difference

Area of Science:

• Health Research Methodology
• Clinical Trial Design
• Biostatistics

Background:

• Accurate sample size calculation is crucial for effective health research trials.
• Specifying the target effect size is a key, yet often underspecified, component of sample size determination.
• Existing methods lack comprehensive guidance on how to define the target effect size.

Discussion:

• The DELTA (Difference ELicitation in TriAls) and DELTA² projects offer evidence-based guidance for systematically determining target effect sizes and sample sizes.
• Guidance development involved expert consultation, review of existing guidelines, and analysis of current research practices.
• Key recommendations include specifying realistic and important differences and performing sensitivity analyses.

Key Insights:

• The DELTA² guidance provides a structured approach to identifying appropriate effect sizes.
• It offers recommendations for conducting sample size calculations and reporting them transparently.
• This systematic approach aims to improve the quality and reproducibility of clinical trials.

Outlook:

• Implementation of this guidance is expected to enhance the power of research studies.
• Improved trial design and reporting will contribute to more reliable scientific evidence.
• The guidance encourages a more thoughtful approach to defining trial objectives and expected outcomes.