1. What is the Wan Arifin Sample Size Formula?

The Wan Arifin formula calculates the minimum sample size required for a study based on desired confidence level, expected proportion, and margin of error. It's commonly used for prevalence studies and surveys.

2. How Does the Calculator Work?

The calculator uses the Wan Arifin formula:

Where:

• \( Z \) — Z-score corresponding to desired confidence level (1.96 for 95% CI)
• \( p \) — Expected proportion (decimal between 0 and 1)
• \( E \) — Desired margin of error (decimal between 0 and 1)

Explanation: The formula calculates the minimum number of participants needed to estimate a population proportion with specified precision and confidence.

3. Importance of Sample Size Calculation

Details: Proper sample size ensures study results are statistically significant, reliable, and representative of the population while avoiding unnecessary resource expenditure.

4. Using the Calculator

Tips:

• For 95% confidence, use Z = 1.96
• When unsure of proportion, use p = 0.5 (most conservative estimate)
• Common error margins are 0.05 (5%) or 0.1 (10%)

5. Frequently Asked Questions (FAQ)

Q1: What Z-score should I use?
A: Common values are 1.96 (95% CI), 1.645 (90% CI), and 2.576 (99% CI). Use higher values for greater confidence.

Q2: What if I don't know the expected proportion?
A: Use 0.5 (50%) as it gives the maximum sample size and is most conservative.

Q3: How does margin of error affect sample size?
A: Smaller margins require larger samples. Halving the margin quadruples the required sample size.

Q4: When is this formula appropriate?
A: For estimating proportions in cross-sectional studies with large populations using simple random sampling.

Q5: What about finite population correction?
A: For small populations (less than 10,000), apply finite population correction to reduce required sample size.