Unadjusted sample variance
Given a sample
![[eq1]](http://images1.statlect.com/unadjusted_sample_variance__1.png)
of
observations, their unadjusted sample variance
is:![[eq2]](http://images1.statlect.com/unadjusted_sample_variance__3.png)
where
is their sample
mean:![[eq3]](http://images1.statlect.com/unadjusted_sample_variance__5.png)
When the
observations are independent, the unadjusted sample variance is a biased
estimator of the population variance. The adjusted sample
variance![[eq4]](http://images1.statlect.com/unadjusted_sample_variance__7.png)
is
instead an unbiased estimator of the population variance.
Go to the lecture entitled Variance estimation for more details and explanations about the concept of unadjusted sample variance.
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