STAT3320 Ali
STAT*3320: Sampling Theory with Applications
1. Introduction: Big Picture
What?
Method of collecting information for the purpose of describing a
population, or comparing characteristics (analyzing data) between two or
more (sub-) populations,

ST3320 Ali
5 Estimating a Ratio (Chapter 6 of text)
5.1 Why would we be interested in a ratio?
(1) Sometimes we are more interested in estimating a ratio R instead of a
mean, total or proportion.
Eg. The average number of hours of TV watched per week by c

ST3320 Ali
3. Probability Sampling
Goal: estimate population parameters (total, mean, variance, proportion)
Q. How accurate of an estimate do we want?
= parameter of interest
B = bound on error of estimation
Error of estimation = | | < B
Pr | | B
1
Q. W

ST3320 Ali F15
Assignment 1
Assignment # 1
Due: Friday, October 2, 2053 in class
1. To estimate how many books in the library need rebinding, a librarian uses a
random number table to randomly select 100 locations on library shelves. He then
walks to each

ST3320 Ali
4 Estimating Sample Size
At some stage of designing a sample survey, the size of the sample must be
stated.
Too large a sample
Too small a sample
Sampling theory provides a framework to think through this problem.
1. What is the population size

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3.8 Inverse Weighting
Recall that in our discussion of totals in Section 3.3, we noted that when sampling
with replacement, we can re-write the total estimator as:
1
= ,
=1
and this estimator is unbiased.
However, when sampling without replace