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.valueOf(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 = (double) Math.sqrt(sum_sq_x/scores1.length);
	double pop_sd_y = (double) 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;
	}