code: protected void setExpectation() {
  		expectation = 0.0;
  		for(Double d: insertStat.keySet()) {
  			expectation += d*(insertStat.get(d)/observationCount);
  		}
  	}
docs: Determines the expectation which is a probabilistic measure,<br>
  estimating the next inserted value based on all values inserted so far.
  @see #expectation