- #1
Nikitin
- 735
- 27
For a set with n points of data, why is the "degree of freedom" of the standard variance n-1? Hell, what does "degree of freedom" actually mean?
Heck, my book "proves" this by saying that since ##\sum_1^n (x_i - \bar{x}) = 0## (obviously), then ##\sum_1^n (x_i - \bar{x})^2## must have n-1 independent pieces of information? Is this connection supposed to be obvious?
My gut feeling agrees that the degree of freedom is n-1, but my brain does not understand. Can somebody explain it formally?
PS: My class statistics book is "Statistics for scientists and engineers, 9th ED". Is it crap (so far I don't like it)? You guys can recommend something better?
Heck, my book "proves" this by saying that since ##\sum_1^n (x_i - \bar{x}) = 0## (obviously), then ##\sum_1^n (x_i - \bar{x})^2## must have n-1 independent pieces of information? Is this connection supposed to be obvious?
My gut feeling agrees that the degree of freedom is n-1, but my brain does not understand. Can somebody explain it formally?
PS: My class statistics book is "Statistics for scientists and engineers, 9th ED". Is it crap (so far I don't like it)? You guys can recommend something better?