public double getFMeasure(int idx) {
		if (idx == 0){
		    return statistic[idxIDrefsFMeasure];
		}else if (idx == 1){
		    return statistic[idxFEsFMeasure];
		}else if (idx == 2){
		    return statistic[idxIDrefsNIFMeasure];
		}else{
		    return -1.0;
		}
	}