org.statcato.statistics.inferential
Class CI2PopProp

java.lang.Object
  extended by org.statcato.statistics.inferential.ConfidenceInterval
      extended by org.statcato.statistics.inferential.CI2PopProp

public class CI2PopProp
extends ConfidenceInterval

Confidence interval class for two population proportions.

Since:
1.0
Version:
%I%, %G%
Author:
Margaret Yau

Field Summary
 
Fields inherited from class org.statcato.statistics.inferential.ConfidenceInterval
center, confidenceLevel
 
Constructor Summary
CI2PopProp(double confidenceLevel, int n1, int n2, double p1, double p2)
          Constructor
 
Method Summary
 double criticalValue()
          Returns the critical value corresponding to the given confidence level.
 double marginOfError()
          Returns the margin of error.
 
Methods inherited from class org.statcato.statistics.inferential.ConfidenceInterval
center, lowerLimit, toString, upperLimit
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

CI2PopProp

public CI2PopProp(double confidenceLevel,
                  int n1,
                  int n2,
                  double p1,
                  double p2)
Constructor

Parameters:
confidenceLevel - confidence level, between 0 and 1
n1 - sample size 1
n2 - sample size 2
p1 - sample proportion 1
p2 - sample proportion 2
Method Detail

marginOfError

public double marginOfError()
Returns the margin of error. E = z_(alpha/2) * sqrt(p1*q1/n1 + p2*q2/n2)

Specified by:
marginOfError in class ConfidenceInterval
Returns:
margin of error

criticalValue

public double criticalValue()
Returns the critical value corresponding to the given confidence level. Uses the z distribution to find z_(alpha/2), where alpha is the significance level (1 - confidence level).

Specified by:
criticalValue in class ConfidenceInterval
Returns:
critical value