public void removeMember(Instance instance) {
		if (numOfMembers == 1) {
			featureVector = new FeatureVector();
			numOfMembers = 0;
		}
		else {
			this.featureVector.scalarDivide(-1.0/numOfMembers);
			this.featureVector.add(instance);
			this.featureVector.scalarDivide(-1.0);
			numOfMembers -= 1;
			this.featureVector.scalarDivide(numOfMembers);
		}
	}