docs: protected double computeMse(Classifier learner, Instances chunk) {
  		double mse_i = 0;
  
  		double f_ci;
  		double voteSum;
  
  		for (int i = 0; i < chunk.numInstances(); i++) {
  			try {
  				voteSum = 0;
  				for (double element : learner.getVotesForInstance(chunk.instance(i))) {
  					voteSum += element;
  				}
  
  				if (voteSum > 0) {
  					f_ci = learner.getVotesForInstance(chunk.instance(i))[(int) chunk.instance(i).classValue()]
  							/ voteSum;
  					mse_i += (1 - f_ci) * (1 - f_ci);
  				} else {
  					mse_i += 1;
  				}
  			} catch (Exception e) {
  				mse_i += 1;
  			}
  		}
  
  		mse_i /= this.chunkSizeOption.getValue();
  
  		return mse_i;
  	}