Re: Review: Revise parallel pg_restore's scheduling heuristic

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