tempco's-----please explain

[geoffery francis james]

in watching the discussion on tempco's two terms have been used.
compensation & coefficient.
my understanding is that to compensate something is to apply an effect to
maintain a constant, like a governor to maintain constant flywheel speed.
a coefficient is a multiplier that indicates how much something will vary
with changing conditions.
in the case of a resistor surely a low coefficient (100ppm/c) would be more
desirable than a large coefficient (3500ppm/c)
recently i had to replace a tempco in an MG1. the local supplier had huge
stocks of metal film resistors (1% 100ppm/c) & precision metal film (1%
15ppm/c).
because the cct called for 1 watt i was restricted to the 100ppm/c
resistor.(precision metal film were rated at .25 watts)
i did not tell the oscillator that it was only getting the cheap resistor
($0.11each) and guess what? it didn't matter.
why all bother with chasing the Q81.
regards 
geoff james (standing by for a lecture)