I am a total Excel/programming novice. I am having a lot of trouble
constructing the simplest macro, and I would love some help. What I
have is a piece of equipment that records the time and extention of a
sample six times a minute, so that the extracted data is something
like:

A B
0.0000 -8.1000e-3
0.0100 -4.5000e-3
0.0100 -1.8000e-3
0.0100 -1.5000e-3
0.0200 -1.8000e-3
0.0200 -1.4000e-3
0.0200 -1.5000e-3
0.0300 -1.0000e-3
0.0300 5.0000e-4
0.0300 2.7000e-3
0.0400 3.7000e-3

Obviously, if this recording goes on for hundreds of hours, it would
result in way to many points to be meaningful. I need to write a macro
that either identifies unique times (I've tried sorting for unique
values, but since the data in column B is different, this doesn't work)
and only retains one point per minute, or, best case scenario, compares
the difference in B column values, and only retains points that meet a
certain minimum difference, so that I only keep points that change
the inflection of the curve. I only need a basic shape; reducing each
data set to 100 points or so would be ideal.

Any help would be fabulous; I'm a graduate student with no experience
in this area whatsoever.