Declaration: 
TCurveFit.QuartilesY (var q1, q2, q3: double): boolean; 
The function QuartilesY returns the quartiles of the distribution of all yvalues entered by EnterStatValue. The first, second, and third quartile are returned in the variable parameters q1, q2, and q3, respectively. Please note that the second quartile q2 is often denoted as the median of the distribution. The function returns a TRUE value if the quartiles are valid. A returned FALSE value indicates a memory overflow problem.

