docs: protected double computeMseR() {
          double p_c;
          double mse_r = 0;
  
          for (int i = 0; i < this.classDistributions.length; i++) {
              p_c = (double) this.classDistributions[i] / (double) this.chunkSize;
              mse_r += p_c * ((1 - p_c) * (1 - p_c));
          }
  
          return mse_r;
      }