Sample Size Calculator for Cross-Sectional Studies
Formula Used (Qualitative Study)
Initial Sample Size:
\[ n = \frac{Z^2 \times P \times (1-P)}{d^2} \]
Adjustment for Finite Population (if applicable):
\[ n = \frac{n}{1 + \frac{(n-1)}{N}} \]
In simpler terms: If you have a limited population size (\(N\)), the sample size is reduced based on how large the initial sample (\(n\)) is compared to \(N\).
| Variable | Description |
|---|---|
| \(n\) | Sample size |
| \(Z\) | Z-score for the confidence level (e.g., 1.96 for 95%) |
| \(P\) | Expected prevalence (as a decimal, e.g., 0.3 for 30%) |
| \(d\) | Margin of error (as a percentage, e.g., 0.05 for ±5%) |
| \(N\) | Sample frame size (total population, if finite) |
Additional adjustments are made for design effect (DEFF) and response rate, if provided.
Also check Sample size calculator for Comparative Study Here