Plus Four Confidence Interval for Proportion Calculator
Use this calculator to compute the plus four confidence interval for population proportion.
Plus Four Confidence Interval Calculator | |
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Sample Size ($n$) | |
Number of successes ($k$) | |
Confidence Level ($1-\alpha$) | |
Results | |
Estimate of proportion: ($\hat{p}$) | |
Standard Error of proportion: ($SE$) | |
Z-critical value: ($Z_{\alpha/2}$) | |
Margin of Error: ($E$) | |
Lower Confidence Limits: | |
Upper Confidence Limits: | |
How to use Plus four method calculator
Step 1 - Enter the sample size
Step 2 - Enter the number of successes
Step 3 - Enter the confidence level
Step 4 - Click on "Calculate" to calculate plus four confidence interval
Step 5 - Click on "Calculate" for Decile Calculator for grouped data
Step 6 - Returns standard error of proportions
Step 7 - Return z critical value
Step 8 - Return margin of error
Step 9 - Return lower confidence limits and upper confidence limits
Plus Four Confidence Interval Formula
$100(1-\alpha)$% plus four confidence interval for population proportion is
$\hat{p} - E \leq p \leq \hat{p} + E$
where,
$\hat{p}=\dfrac{X+2}{n+4}$
is the estimate of population proportion based on plus four rule,$E = Z_{\alpha/2} \sqrt{\dfrac{\hat{p}(1-\hat{p})}{n+4}}$
is the margin of error,$1-\alpha$
is the confidence coefficient,$Z_{\alpha/2}$
is the critical value of $Z$.
Reference
You can read step by step tutorial on Plus Four Confidence Interval for Proportion, tutorial will help you to understand step by step procedure to construct a plus four confidence interval for population proportion and confidence interval for proportion examples.