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# Plus Four Confidence Interval for Proportion Calculator

## 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
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.

Plus Four Confidence Interval for Proportion

Plus Four Confidence Interval for Proportion Examples