PokerTracker

which is the function of the checkbox "essential statistic"?

That box flags those statistics we believe are the most basic and most important stats - the stats which you could definitely never do without. Anytime you can search for a stat in a Configure Report-type menu there's a checkbox for showing Essential stats. This is to give users who want a shortened list of the most important stats a place to start. Our entire list is very long - this is much shorter (it's like 1/8th of the total list I believe).