Use R code. Dataset survey in MASS package contains the responses of 237 Statist
ID: 3310867 • Letter: U
Question
Use R code. Dataset survey in MASS package contains the responses of 237 Statistics students at the University of Adelaide to a number of questions. One tested if how much the student smokes (smoke) and how often the student exercises (exer) are independent using chi-sq test. The result, however, got a warning message: In chisq.test(tbl) : Chi-squared approximation may be incorrect. So, 'none' and 'some' categories in 'exer' variable are combined. the following table is the reallocated data:
[,1] [,2]
Heavy 7 4
Never 87 102
Occas 12 7
Regul 9 8
Report the test statistic using the table above. (up to three decimal places, please)
From the previous question, what is the expected value of cell (1,1) (Heavy & [,1])? (up to three decimal places, please)
Explanation / Answer
applyin chi square test on above data:
test statistic =3.233
expected value of cell (1,1) =5.360
Observed O [,1] [,2] Total heavy 7 4 11 never 87 102 189 occas 12 7 19 regualr 9 8 17 Total 115 121 236 Expected E=rowtotal*column total/grand total [,1] [,2] Total heavy 5.360 5.640 11 never 92.097 96.903 189 occas 9.258 9.742 19 regualr 8.284 8.716 17 Total 115 121 236 chi square =(O-E)^2/E [,1] [,2] Total heavy 0.5017 0.4768 0.978 never 0.2821 0.2681 0.550 occas 0.8118 0.7715 1.583 regualr 0.0619 0.0588 0.121 Total 1.658 1.575 3.2328Related Questions
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