Sample size calculations for continuous outcomes in clinical nutrition

Area of Science:

• Nutrition Science
• Biostatistics
• Epidemiology

Background:

• Sample size calculations are vital for the planning of randomized trials and observational studies in nutrition research.
• Limited literature exists specifically on sample size calculations within the nutritional science field.
• Accurate sample size determination ensures statistical power and efficient resource utilization.

Approach:

• This article reviews common methodologies for sample size calculations in nutrition research.
• Approximate formulas are utilized to explain core concepts and demonstrate practical applications using literature examples.
• The review extends basic two-group comparison calculations to various study designs, including multi-group and multiple outcome scenarios.

Key Points:

• Sample size calculations for different study designs are presented as extensions of the basic two-group comparison.
• Modifications to significance levels and the use of scaling factors are discussed for complex designs.
• Challenging designs, such as cluster-randomized trials, may necessitate consultation with a biostatistician.

Conclusions:

• The review provides a foundational understanding of sample size calculations for nutrition research.
• Researchers are guided on adapting standard methods for diverse and complex study designs.
• Final sample size determination involves statistical considerations alongside logistical and resource constraints.