java实现t检验

深碍√TFBOYSˉ_ 2023-06-26 10:59 5阅读 0赞

### 文章目录 ###

*   *  场景
     *  maven依赖
     *  用法
     *  实现代码

## 场景 ##

用于两个总体均值之间的比较。

## maven依赖 ##

<dependency>
    			<groupId>net.sf.jsci</groupId>
    			<artifactId>jsci</artifactId>
    			<version>1.2</version>
    		</dependency>
    		
    		<dependency>
    			<groupId>org.apache.commons</groupId>
    			<artifactId>commons-math3</artifactId>
    			<version>3.6.1</version>
    		</dependency>
    
    	</dependencies>

## 用法 ##

public class TtestDemo {
    
    	/**
    	 * two-sided test
    	 * @param args
    	 */
    	public static void main(String[] args) {
    		double[] x= {300,280,344,385,372,360,288,321,376,290,301,283};
    		double[] y= {274,220,308,336,198,300,315,258,318,310,332,263};
    		Ttest t=new Ttest(x, y);
    		System.out.println(t.getPValue());
    
    	}
    
    }

## 实现代码 ##

package com.math.statistics;
    import org.apache.commons.math3.stat.descriptive.moment.StandardDeviation;
    
    import JSci.maths.statistics.TDistribution;
    
    public class Ttest {
    	
    	private double[] x;
    	
    	private double[] y;
    	StandardDeviation standardDeviation =new StandardDeviation();
    	
    	public Ttest(double[] x, double[] y) {
    		super();
    		this.x = x;
    		this.y = y;
    	}
    	public int getXSize() {
    		return x==null?0:x.length;
    	}
    	public int getYSize() {
    		return y==null?0:y.length;
    	}
    	public double getXMean() {
    		int n=x.length;
    		double sum=0;
    		for (double d : x) {
    			sum=sum+d;
    		}
    		return sum/n;
    	}
    	public double getYMean() {
    		int n=y.length;
    		double sum=0;
    		for (double d : y) {
    			sum=sum+d;
    		}
    		return sum/n;
    	}
    	public double getStandard(double[] x) {
    		return standardDeviation.evaluate(x);
    	}
    	public double calculateTvalue() {
    		double a=getXMean()-getYMean();
    		double q1=getStandard(x);
    		double q2=getStandard(y);
    		double s1=q1*q1;
    		double s2=q2*q2;
    		double b=Math.sqrt(s1/x.length+s2/y.length);
    		return a/b;
    	}
    	public int getDegreesOfFreedom() {
    		double q1=getStandard(x);
    		double q2=getStandard(y);
    		double s1=q1*q1;
    		double s2=q2*q2;
    		double a=(s1/x.length+s2/y.length)*(s1/x.length+s2/y.length);
    		double b=((s1/x.length)*(s1/x.length))/(x.length-1)+((s2/y.length)*(s2/y.length))/(y.length-1);
    		Double free=a/b;
    		return free.intValue();
    	}
    	public double getPValue() {
    		int free=getDegreesOfFreedom();
    		double t=calculateTvalue();
    		TDistribution td=new TDistribution(free);
    		double cumulative = td.cumulative(t);
    		double p;
    		if(t>0) {
    			p=(1-cumulative)*2;
    		}else {
    			p=cumulative*2;
    		}
    		return p;
    	}
    }