Write a java program to compute correlation?

Answer 1

public class Correlation {

public static double getPearsonCorrelation(double[] scores1,double[] scores2){

double result = 0;

double sum_sq_x = 0;

double sum_sq_y = 0;

double sum_coproduct = 0;

double mean_x = scores1[0];

double mean_y = scores2[0];

for(int i=2;i<scores1.length+1;i+=1){

double sweep =(double)(i-1)/i;

double delta_x = scores1[i-1]-mean_x;

double delta_y = scores2[i-1]-mean_y;

sum_sq_x += delta_x * delta_x * sweep;

sum_sq_y += delta_y * delta_y * sweep;

sum_coproduct += delta_x * delta_y * sweep;

mean_x += delta_x / i;

mean_y += delta_y / i;

}

double pop_sd_x = Math.sqrt(sum_sq_x/scores1.length);

double pop_sd_y = Math.sqrt(sum_sq_y/scores1.length);

double cov_x_y = sum_coproduct / scores1.length;

result = cov_x_y / (pop_sd_x*pop_sd_y);

return result;

}

}