🚀 go-pugleaf

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Can someone explain why calculating the Standard Deviation (SD),
for small samples, with (n-1) in the denominator is better than
doing so with (n) in the denominator?  I'm sure that there's
a perfectly good reason for doing so.  But we, lowly engineers
aren't usually told the reason.  Thanks now, for your response later.;-)

RESPONSE (and my own query):

The variance increases as a function of sample size.  That is, a small
sample will systematically underestimate the population variance (if we
estimate the population variance with denominator N-1).  Using this
reduced denominator therefore has the effect of increasing the variance
estimate.

My question:  why does a small sample underestimate the population variance?  

daniel read