Calculadora de Tamaño de Muestra — Fórmula
## How to Calculate Required Sample Size
### Formula
**n = (z * sigma / E)^2**
where E is the desired margin of error, z is the critical value for the confidence level, and sigma is the population standard deviation. Always round up to the next whole number since you cannot have a fractional observation.
### Formula
**n = (z * sigma / E)^2**
where E is the desired margin of error, z is the critical value for the confidence level, and sigma is the population standard deviation. Always round up to the next whole number since you cannot have a fractional observation.
Ejemplo Resuelto
You want a 95% CI with margin of error 3 and estimated SD 15. How many observations are needed?
- n = (z * sigma / E)^2
- n = (1.96 * 15 / 3)^2
- n = (9.8)^2
- n = 96.04
- Round up: n = 97 observations needed