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.

MATLAB: An Introduction with Applications
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Chapter1: Starting With Matlab
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a. First check the assumptions:
1. The samples are independent samples taken from two or more populations (0-29 WLM, 30-89 WLM, 90-120 WLM). We
assume these samples are simple random samples.
2. Each outcome falls into exactly one of several categories (Yes/No) with the categories being the same in all treatment
populations.
3. Now check if the third requirement is satisfied:
O The expected frequency for each cell is greater than 5, therefore the requirements for a x? test are satisfied.
O The expected frequency for at least one cell is less than 5 , therefore the requirements for a x? test are not satisfied.
We don't need to check the expected frequency of cells for the requirements for a x? test.
The minimum observed frequency for each cell is greater than 5, therefore the requirements for a x? test are
satisfied.
Transcribed Image Text:a. First check the assumptions: 1. The samples are independent samples taken from two or more populations (0-29 WLM, 30-89 WLM, 90-120 WLM). We assume these samples are simple random samples. 2. Each outcome falls into exactly one of several categories (Yes/No) with the categories being the same in all treatment populations. 3. Now check if the third requirement is satisfied: O The expected frequency for each cell is greater than 5, therefore the requirements for a x? test are satisfied. O The expected frequency for at least one cell is less than 5 , therefore the requirements for a x? test are not satisfied. We don't need to check the expected frequency of cells for the requirements for a x? test. The minimum observed frequency for each cell is greater than 5, therefore the requirements for a x? test are satisfied.
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.
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