Sample Size Calculator: Free Statistics Research Tool
Sample Size Calculator
Determine the ideal number of participants needed for your research survey or poll.
RECOMMENDED SAMPLE SIZE
Sample Size: 385
Based on 95% confidence level and 5% margin of error.
Why is Sample Size Important in Research?
When conducting scientific studies, market research, or public opinion polls, it is rarely practical to survey an entire population. Instead, researchers select a smaller subset known as a sample. Calculating the correct Sample Size ensures that your findings are statistically valid, reliable, and representative of the broader population without wasting resources. Our free online calculator automates this complex statistical computation.
Core Statistical Formula
The standard formula for calculating sample size incorporates the chosen confidence level score ($Z$), the margin of error ($e$), and the estimated population proportion ($p$).
Cochran's Sample Size Formula (Infinite Population):
$n = \frac{Z^2 \cdot p \cdot (1 - p)}{e^2}$
$n = \frac{Z^2 \cdot p \cdot (1 - p)}{e^2}$
Frequently Asked Questions (FAQ)
Q: What happens if I decrease the margin of error?
A: A smaller margin of error (e.g., changing from 5% to 2%) requires a significantly larger sample size to maintain statistical accuracy.
A: A smaller margin of error (e.g., changing from 5% to 2%) requires a significantly larger sample size to maintain statistical accuracy.
Q: What confidence level should I use?
A: A 95% confidence level is the international academic standard for most social science and commercial research studies.
A: A 95% confidence level is the international academic standard for most social science and commercial research studies.
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