Sample Size Calculator for Pilot Study
Below is a basic template for a sample size table, including common parameters and considerations:
Sample Size Calculation Table for a Pilot Study
| Parameter | Description | Value |
|---|---|---|
| Study Design | Type of study (e.g., randomized controlled trial, cohort) | |
| Outcome Measure | Primary outcome variable | |
| Expected Effect Size | Estimated effect size based on prior research or pilot data | |
| Variability | Standard deviation of the outcome measure | |
| Significance Level (α) | Probability of Type I error (commonly 0.05) | |
| Power (1 – β) | Probability of detecting an effect if one exists (commonly 0.80) | |
| Sample Size Calculation Method | Method used (e.g., formulas, software) | |
| Initial Sample Size Estimate | Calculated sample size for pilot study | |
| Adjusted Sample Size | Adjusted for expected dropouts or non-response | |
| Final Sample Size | Recommended sample size for pilot study |
Key Considerations
- Study Design: This affects how sample size is calculated. Different designs (e.g., parallel groups, crossover) may require different approaches.
- Expected Effect Size: This is crucial; smaller effect sizes typically require larger samples.
- Variability: Higher variability in the outcome measure requires a larger sample size.
- Significance Level and Power: Common values are α = 0.05 and power = 0.80, but these can be adjusted based on the study’s requirements.
- Dropout Rate: Adjust the sample size to account for participants who may drop out or not respond, typically by increasing the initial estimate by a certain percentage.
Example Calculation
For a pilot study with the following parameters:
- Study Design: Randomized Controlled Trial
- Outcome Measure: Blood Pressure Reduction
- Expected Effect Size: 5 mmHg
- Variability: 10 mmHg
- Significance Level (α): 0.05
- Power (1 – β): 0.80
Using a standard sample size formula (for a two-sample t-test), you might calculate an initial sample size of around 30 participants per group. Adjusting for a 20% dropout rate would lead to a final recommendation of approximately 36 participants per group.