When to use which formula for sample variance?
Jan 7, 2025 · For hypothesis tests where we compute a t-statistic or F-statistic, and possibly you use a formula for them where they use a sample variance s2 s 2 then you should be careful to use the …
covariance - Intuition behind the formula for the variance of a sum of ...
May 15, 2018 · The standard deviation acts much like a length, and the variance like length squared. Independence corresponds to being orthogonal, while perfect correlation corresponds with scalar …
What is the difference between N and N-1 in calculating population ...
One reserved observation is "-1" and so you have N-1 in computing the variance estimate. The unbiased estimate is called sample variance (not to be confused with the sample's variance) which is an argot; …
Variance of product of multiple independent random variables
May 5, 2021 · Variance of product of multiple independent random variables Ask Question Asked 12 years, 10 months ago Modified 2 years, 4 months ago
intuition - Intuitive explanation for dividing by $n-1$ when ...
Aug 28, 2015 · The variance estimator makes use of the sample mean and as a consequence underestimates the true variance of the population. Dividing by n-1 instead of n corrects for that bias.
why sample variance has has n-1 in the denominator?
Feb 25, 2016 · If the sample variance is larger than there is a greater chance that it captures the true population variance. That is why when you divide by $ (n-1)$ we call that an unbiased sample estimate.
Formula for the variance of the product of two random variables
Mar 22, 2022 · 5 The formula you are asserting is not correct (as shown in the counter-example by Dave), and it is notable that it does not include any term for the covariance between powers of the …
The linearity of variance - Cross Validated
Dec 4, 2015 · 38 The problem with your line of reasoning is "I think we can always assume X X to be independent from the other X X s." X X is not independent of X X. The symbol X X is being used to …
Understanding "variance" intuitively - Cross Validated
Oct 2, 2014 · This formula is called "Variance" in statistics. And it fits Much better to estimate the spread of our thermometer (or whatever) values, than taking just the maximum distance.
Difference between Pooled variance and Combined variance
Dec 17, 2021 · A first difference between the pooled and combined variance formulas you have displayed is that the pooled variance formula given here contains what is known as a "degrees of …