rJava : プログラミング(10) F Test(２群における等分散検定)

一人の手術者の評価の前半、後半で得点の差があるか検定するために、２群の得点が等分散かどうかF検定をやってみます。

F検定：対象３７件
帰無仮説：2群間の分散に差がない(等分散である)
 今回の２つの群は
[39.0, 40.0, 39.0, 38.0, 38.0, 43.0, 48.0, 43.0, 41.0, 44.0, 35.0, 36.0, 37.0, 30.0, 46.0, 40.0, 44.0, 40.0]
[45.0, 36.0, 45.0, 38.0, 39.0, 45.0, 40.0, 44.0, 48.0, 45.0, 45.0, 46.0, 40.0, 44.0, 37.0, 45.0, 48.0, 44.0, 43.0]
となり、
一つ目のsummaryは、意味は(Min    最小値, 1st Qu    第一四分位数, Median    中央値, Mean    平均値, 3rd Qu    第三四分位数, Max    最大値)
(30.0, 38.0, 40.0, 40.06, 43.0, 48.0)
 ２つ目は
(36.0, 40.0, 44.0, 43.0, 45.0, 48.0)
最小値も平均も高いので、後半の方が良さそうだけど、t検定をする予定。そのために等分散を検定しておく。

$ vi JRITest14.java
$ javac JRITest14.java
$ java -Djava.library.path=/usr/lib64/R/library/rJava/jri/ JRITest14

[VECTOR ([REAL* (1.4314578005115088)], [INT* (17, 18)], [REAL* (0.45734976337721367)], [REAL* (0.547029015180649, 3.7965176255066506)], [REAL* (1.4314578005115088)], [REAL* (1.0)], [STRING "two.sided"], [STRING "F test to compare two variances"], [STRING "c_group1 and c_group2"])]

p-value = 0.45734976337721367
なので帰無仮説が採択。よって等分散が言える。

[JRITest14.java]
今回のSQL文
String sql = "SELECT * FROM operations WHERE category = 0 AND evaluator <=15 and operator =6";

import org.rosuda.JRI.REXP;
import org.rosuda.JRI.Rengine;
import java.sql.*;
import java.util.Arrays;

public class JRITest14 {

        public static void main(String[] args)
        {
                MySQL mysql = new MySQL();
                Rengine re = new Rengine( new String[]{"--no-save"}, false, null );
                ResultSet rs = mysql.selectOperations();

                int N = 37;
                double group1 [] = new double[N/2];
                double group2 [] = new double[N/2+1];//**注意i:奇数の時は+1**

                int index = 0;
                try {
                        while(rs.next()){
                                if(index < (int)(N/2)){
                                        group1[index] = rs.getDouble("value");
                                }else if(index >= (int)(N/2)){
                                        group2[index-(int)(N/2)] = rs.getDouble("value");
                                }
                                index ++;
                        }
                } catch (SQLException e) {
                        e.printStackTrace();
                }

                System.out.println(Arrays.toString(group1));
                System.out.println(Arrays.toString(group2));

                StringBuffer buf1 = new StringBuffer();
                buf1.append("c_group1<-c(");
                for(int i = 0; i < group1.length; i++){
                        if(i == group1.length-1)
                                buf1.append(group1[i]+")");
                        else
                                buf1.append(group1[i]+",");
                }
                String c_group1 = buf1.toString();
                re.eval(c_group1);

                REXP x1 = re.eval("summary(c_group1)");
                System.out.println(x1);
                double [] ary1 = x1.asDoubleArray();
                for (int i = 0; i < ary1.length; i++) {
                        System.out.println(ary1[i]);
                }

                StringBuffer buf2 = new StringBuffer();
                buf2.append("c_group2<-c(");
                for(int i = 0; i < group2.length; i++){
                        if(i == group2.length-1)
                                buf2.append(group2[i]+")");
                        else
                                buf2.append(group2[i]+",");
                }
                String c_group2 = buf2.toString();
                re.eval(c_group2);

                REXP x2 = re.eval("summary(c_group2)");
                System.out.println(x2);
                double [] ary2 = x2.asDoubleArray();
                for (int i = 0; i < ary2.length; i++) {
                        System.out.println(ary2[i]);
                }

                REXP x3 = re.eval("var.test(c_group1, c_group2)");
                System.out.println(x3);
                re.end();
        }
}

参考
http://kusuri-jouhou.com/statistics/fkentei.html
http://cse.naro.affrc.go.jp/takezawa/r-tips/r/65.html
http://monge.tec.fukuoka-u.ac.jp/r_analysis/test_t03.html