Comparing two estimators.

#1
Q: Suppose we take a random sample of size n from a N (0,1) populations. Consider two estimators of simga squared.

Two estimators equations and tables can be seen here:
http://imgur.com/gfZK2wJ

Compare of s^2 and SM^2 for their bias, variances and MSE.

I don't really know how to approach this problem. How can there be negative bias?
 
Last edited:

Dason

Ambassador to the humans
#2
Bias is just "expected value of the estimator - True value of the parameter". If the estimator under estimates the true parameter (on average) it has negative bias.
 
#3
Okay thanks! So does a value closer to 0 means there is less bias and the larger value of variance means its more variable? and for MSE, shouldn't a lower value indicate less error?

I know that when n increases the s2 and S^2M becomes more similar due to the central limit therom.