52 Statistics and the Casio fx-9750G Plus • Activity 11 Copyright © Casio, Inc.
Activity 11
Exit Polls
Topic Area: Hypothesis Tests—Chi-square, Two-way Tables
NCTM Standards:
• Develop and evaluate inferences and predictions that are based on data
• Use simulations to explore the variability of sample statistics from a
known population and to construct sampling distributions (9-12)
• Understand how sample statistics reflect the values of population
parameters and use sampling distributions as the basis for informal
inference (9-12)
Objective
The students will be able to support or reject a null hypothesis based on given
data and calculations of confidence using a Chi-square distribution.
Introduction
The Chi-squared test is used to figure out if the rows of a set of data are contin-
gent upon the columns in that same set of data, or a test of independence. In this
activity, the students are presented with a set of "exit poll" data showing the num-
ber of votes for three different candidates at the sophomore, junior, and senior
level. The data was taken by a random poll of students after the vote. The null
hypothesis in this case states that the class level is independent of the candidate
voted for. If this null hypothesis is rejected, the students could say that there was
a difference in candidate preference between the three classes of students.
Use the following descriptions to go through the chi-square test manually:
In order to calculate the chi-square test, the student needs to calculate the row
and column totals and calculate the expected cell frequencies using the equation:
where E
cell1,A
is the expected frequency for the cell in the first column and the
first row,
T is the total number in the row or column, and N is the total number
in the entire table.
Teaching Notes
E
cell1,A
=
T
1
– T
A
N
35
(30.449)
40
(35.986)
25
(33.564)
100
33
(31.058)
38
(36.705)
31
(34.235)
102
20
(26.491)
26
(31.307)
41
(29.2)
87
88
104
97
289
Candidate 1 Candidate 2 Candidate 3 Total
Sophomore
Junior
Senior
Total
(28 pages)
(18 pages)
(2 pages)
(31 pages)
Whitehaus Collection WHTTSCR3-9771SPR-ABRAS Installation Guide,
1 stránky
Manymanuals.com
Manymanuals.de
Manymanuals.fr
Manymanuals.it
Manymanuals.pl
Manymanuals.cz
Manymanuals.es
Manymanuals-pt.com
Comments to this Manuals