Can I freely set a range criterion(a) for counting? e.g. for the following
data, can I set < 80 or 100 or <120 and 80 DYNAMICALLY? I can do that by
adding columns to check the conditions but it then constrains my mind as I
cannot see the statistics in real time. Thanks.

GFR_Base
80.161
86.994
128.392
108.492
126.251