1. The incidence of cancer among phosphate mine workers and their exposure to radiation was investigated. Cancer incidence was recorded among 60 phosphate mine workers who had 0-29 working level months (WLM) of exposure, 60 phosphate mine workers who had 30-89 WLM of exposure, and 60 phosphate mine workers who had 90-120 WLM of exposure. The number of cancer incidences for each group are presented in Table 1. Table 1: Two-way Table of Counts Cancer Incidence Exposure Level Yes No Total 0-29 WLM 20 40 60 30-89 WLM 33 27 60 90-120 WLM 43 17 60 Total 96 84 180 Perform a x? test, at the 5% level of significance, whether cancer incidence rates differ between the three levels of radiation among phosphate mine workers.

Linear Algebra: A Modern Introduction
4th Edition
ISBN:9781285463247
Author:David Poole
Publisher:David Poole
Chapter2: Systems Of Linear Equations
Section2.4: Applications
Problem 1EQ: 1. Suppose that, in Example 2.27, 400 units of food A, 600 units of B, and 600 units of C are placed...
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1. The incidence of cancer among phosphate mine workers and their exposure to radiation was investigated. Cancer
incidence was recorded among 60 phosphate mine workers who had 0-29 working level months (WLM) of exposure, 60
phosphate mine workers who had 30-89 WLM of exposure, and 60 phosphate mine workers who had 90-120 WLM of
exposure. The number of cancer incidences for each group are presented in Table 1.
Table 1: Two-way Table of Counts
Cancer Incidence
Exposure Level
Yes
No
Total
0-29 WLM
20
40
60
30-89 WLM
33
27
60
90-120 WLM
43
17
60
Total
96
84
180
Perform a x? test, at the 5% level of significance, whether cancer incidence rates differ between the three levels of
radiation among phosphate mine workers.
Transcribed Image Text:1. The incidence of cancer among phosphate mine workers and their exposure to radiation was investigated. Cancer incidence was recorded among 60 phosphate mine workers who had 0-29 working level months (WLM) of exposure, 60 phosphate mine workers who had 30-89 WLM of exposure, and 60 phosphate mine workers who had 90-120 WLM of exposure. The number of cancer incidences for each group are presented in Table 1. Table 1: Two-way Table of Counts Cancer Incidence Exposure Level Yes No Total 0-29 WLM 20 40 60 30-89 WLM 33 27 60 90-120 WLM 43 17 60 Total 96 84 180 Perform a x? test, at the 5% level of significance, whether cancer incidence rates differ between the three levels of radiation among phosphate mine workers.
e. Fill in the gaps and calculate. The observed statistic is given by:
2 (Oj - E)?
-ΣΣ
(Oij – Eij)
Eij
x²
i=1 j=1
(20 – 32)2
(40 – 28)2
(33 – 32)2
(27 – 28)2
(43–
(17–
32
28
32
28
32
16.237
O 17.812
O 12.451
O 19.245
Transcribed Image Text:e. Fill in the gaps and calculate. The observed statistic is given by: 2 (Oj - E)? -ΣΣ (Oij – Eij) Eij x² i=1 j=1 (20 – 32)2 (40 – 28)2 (33 – 32)2 (27 – 28)2 (43– (17– 32 28 32 28 32 16.237 O 17.812 O 12.451 O 19.245
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