/******************************************************************************
* Name: Kevin Wayne
* NetID: wayne
* Precept: P00
*
* Description: Computes the G-statistic of the observed frequencies
* and the expected frequencies.
******************************************************************************/
public class GStatistic {
public static void main(String[] args) {
double gStatistic = 0.0;
int numberOfNonzeros = 0;
// read data from standard input and update statistics
int n = StdIn.readInt();
for (int i = 0; i < n; i++) {
int x = StdIn.readInt();
int y = StdIn.readInt();
if (y != 0) numberOfNonzeros++;
if (x != 0) gStatistic += 2.0 * x * Math.log(1.0 * x / y);
}
// print results to standard output
int degreesOfFreedom = numberOfNonzeros - 1;
System.out.printf("degrees of freedom = %d\n", degreesOfFreedom);
System.out.printf("G-statistic = %.4f\n", gStatistic);
}
}