Sam Mason <sam@samason.me.uk> writes:
> t = 0.54 ((avg1 - avg2) / (stddev * sqrt(2/samples)))
> We then have to choose how certain we want to be that they're actually
> different, 90% is a reasonably easy level to hit (i.e. one part in ten,
> with 95% being more commonly quoted). For 20 samples we have 19 degrees
> of freedom--giving us a cut-off[1] of 1.328. 0.54 is obviously well
> below this allowing us to say that there's no "statistical significance"
> between the two samples at a 90% level.
Hmm, so what about 95% or 99% confidence?
regards, tom lane