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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

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