code: public static double getLowerBoundForBoverA(final Sketch sketchA, final Sketch sketchB) {
      final double thetaA = sketchA.getTheta();
      final double thetaB = sketchB.getTheta();
      checkThetas(thetaA, thetaB);
  
      final int countB = sketchB.getRetainedEntries(true);
      final int countA = (thetaB == thetaA) ? sketchA.getRetainedEntries(true)
          : sketchA.getCountLessThanTheta(thetaB);
  
      if (countA <= 0) { return 0; }
  
      return BoundsOnRatiosInSampledSets.getLowerBoundForBoverA(countA, countB, thetaB);
    }
docs: Gets the approximate lower bound for B over A based on a 95% confidence interval
  @param sketchA the sketch A
  @param sketchB the sketch B
  @return the approximate lower bound for B over A