code: public static double getLowerBound(final int numStdDev, final Memory srcMem) {
      return Sketch.lowerBound(getRetainedEntries(srcMem), getThetaLong(srcMem), numStdDev, getEmpty(srcMem));
    }
docs: Gets the approximate lower error bound from a valid memory image of a Sketch
  given the specified number of Standard Deviations.
  This will return getEstimate() if isEmpty() is true.
  
  @param numStdDev
  <a href="{@docRoot}/resources/dictionary.html#numStdDev">See Number of Standard Deviations</a>
  @param srcMem <a href="{@docRoot}/resources/dictionary.html#mem">See Memory</a>
  @return the lower bound.