1. What is ICC Sample Size Calculation?

The ICC (Intraclass Correlation Coefficient) sample size calculation determines the number of participants needed to achieve reliable results in reliability studies, accounting for expected variability (standard deviation) and desired precision (error margin).

2. How Does the Calculator Work?

The calculator uses the sample size equation:

Where:

• \( Z \) — Z-score for desired confidence level (1.96 for 95% CI)
• \( SD \) — Standard deviation of measurements
• \( E \) — Desired margin of error

Explanation: The equation calculates how many participants are needed to estimate the ICC with specified precision, considering the variability in your data.

3. Importance of Sample Size Calculation

Details: Proper sample size ensures your reliability study has adequate power to detect meaningful ICC values while avoiding excessive resource use on unnecessarily large samples.

4. Using the Calculator

Tips: Enter Z-score (typically 1.96 for 95% CI), estimated standard deviation from pilot data, and acceptable error margin. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What Z-score should I use?
A: For 95% confidence, use 1.96. For 90% confidence use 1.645, and for 99% use 2.576.

Q2: How to estimate standard deviation?
A: Use pilot study data or literature values for similar measurements in your target population.

Q3: What's a reasonable error margin?
A: Typically 0.05-0.10 for ICC studies, but depends on your precision requirements.

Q4: Does this account for multiple raters?
A: No, this is the basic formula. For multiple raters, more complex calculations are needed.

Q5: What if my calculated sample size is very large?
A: Consider increasing your acceptable error margin or using more precise measurement tools to reduce variability.