/*
* This file is part of ADDIS (Aggregate Data Drug Information System).
* ADDIS is distributed from http://drugis.org/.
* Copyright © 2009 Gert van Valkenhoef, Tommi Tervonen.
* Copyright © 2010 Gert van Valkenhoef, Tommi Tervonen, Tijs Zwinkels,
* Maarten Jacobs, Hanno Koeslag, Florin Schimbinschi, Ahmad Kamal, Daniel
* Reid.
* Copyright © 2011 Gert van Valkenhoef, Ahmad Kamal, Daniel Reid, Florin
* Schimbinschi.
* Copyright © 2012 Gert van Valkenhoef, Daniel Reid, Joël Kuiper, Wouter
* Reckman.
* Copyright © 2013 Gert van Valkenhoef, Joël Kuiper.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.drugis.addis.entities.relativeeffect;
import org.drugis.addis.entities.ContinuousMeasurement;
public class BasicMeanDifference extends AbstractBasicRelativeEffect<ContinuousMeasurement> {
/**
* The MeanDifference of two ContinuousMeasurements.
* In a forest plot, the numerator will be on the right and the denominator on the left.
* @param baseline
* @param subject
*/
public BasicMeanDifference(ContinuousMeasurement baseline, ContinuousMeasurement subject) throws IllegalArgumentException {
super(baseline, subject);
}
private double getMu() {
return d_subject.getMean() - d_baseline.getMean();
}
@Override
public Double getError() {
return Math.sqrt(square(d_subject.getStdDev()) / (double) d_subject.getSampleSize()
+ square(d_baseline.getStdDev()) / (double) d_baseline.getSampleSize());
}
private Double square(double x) {
return x*x;
}
public String getName() {
return "Mean Difference";
}
@Override
protected Integer getDegreesOfFreedom() {
return getSampleSize() - 2;
}
public Distribution getDistribution() {
return new TransformedStudentT(getMu(), getError(), getDegreesOfFreedom());
}
@Override
public AxisType getAxisType() {
return AxisType.LINEAR;
}
}