Show that S2 is unbiased for o2. Find variance of S2. Find the bias of ô? and the variance of ô?. Show that Mean Square Error (MSE) of ô? is smaller than MSE of S2.

Big Ideas Math A Bridge To Success Algebra 1: Student Edition 2015
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ISBN:9781680331141
Author:HOUGHTON MIFFLIN HARCOURT
Publisher:HOUGHTON MIFFLIN HARCOURT
Chapter4: Writing Linear Equations
Section: Chapter Questions
Problem 12CR
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B) Let X1,X2, .,Xn be a random sample from a N(u, o2) population with both parameters
unknown. Consider the two estimators S2 and ô? for o? where S2 is the sample variance, i.e.
s2 =E,(X, – X)² and ở² = 'E".,(X1 – X)². [X = =E-, X, is the sample mean].
%3D
n-1
Li%3D1
[Hint:
a2
(п-1)52
-~x~-1 which has mean (n-1) and variance 2(n-1)]
i)
Show that S2 is unbiased for o2. Find variance of S2.
ii)
Find the bias of 62 and the variance of ô2.
iii)
Show that Mean Square Error (MSE) of ô2 is smaller than MSE of S?.
iv)
Show that both S2 and ô? are consistent estimators for o?.
Transcribed Image Text:B) Let X1,X2, .,Xn be a random sample from a N(u, o2) population with both parameters unknown. Consider the two estimators S2 and ô? for o? where S2 is the sample variance, i.e. s2 =E,(X, – X)² and ở² = 'E".,(X1 – X)². [X = =E-, X, is the sample mean]. %3D n-1 Li%3D1 [Hint: a2 (п-1)52 -~x~-1 which has mean (n-1) and variance 2(n-1)] i) Show that S2 is unbiased for o2. Find variance of S2. ii) Find the bias of 62 and the variance of ô2. iii) Show that Mean Square Error (MSE) of ô2 is smaller than MSE of S?. iv) Show that both S2 and ô? are consistent estimators for o?.
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