Sampling Distribution
Standard Error of Proportion
Result
Tips about Hypothesis testing for Mean when σ known:
Definations
- The standard error of the proportion measures the variability of a sample proportion from the true population proportion. When dealing with a finite population, the calculation needs to account for the population size to be more accurate. This adjustment is known as the finite population correction factor.
- The formula for the standard error of the proportion with the finite population correction factor is: \[ \sigma_p = \sqrt{\frac{p(1 - p)}{n}} \times \sqrt{\frac{N - n}{N - 1}} \]
- For an unknown population proportion (using sample proportion: \[ \sigma_{\hat{p}} = \sqrt{\frac{\hat{p}(1 - \hat{p})}{n}} \times \sqrt{\frac{N - n}{N - 1}} \] Where:
\(p\) is Population Proportion
\(\hat{p}\) is sample proportion \(n\) is a sample size \(N\) is a population size
Common Errors:
- Ignoring Finite Population Correction:
- When the sample size is a significant fraction of the population (n/N ≥ 5%), ignoring the correction factor can lead to overestimating the variability.
- Misidentifying Proportions:
- Ensure you correctly distinguish between sample proportion (\(\hat{p}\)) and population proportion (p).
- Incorrect Formula Application:
- Use the finite population correction only when the sample size is a significant fraction of the population. For small samples relative to the population, the correction factor has negligible impact.
- Rounding Errors:
- Use precise values during calculations to avoid rounding errors that can affect the final result.
Additional Tips
- When to Use Correction Factor:
- Apply the finite population correction factor if your sample size is more than 5% of the total population. For large populations where n/N < 5%, the correction factor is minimal and can be ignored.
- Verify Population Size:
- Ensure the total population size (N) is correctly identified, as this significantly impacts the correction factor.
- Increasing the sample size
- If the sample size increases and close to the popoulation size then the standard error become close to zero. and if it is the n equals with the N then the standard erro will be 0.
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