R Notebook

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Example 1

Premed=c(13,19,90)#frequencie in first row 
Others=c(8,11,359)#frequencies in second row
college.table=rbind(Premed, Others)#make a table
print(college.table) #not necessary  

##        [,1] [,2] [,3]
## Premed   13   19   90
## Others    8   11  359

test_Example1=chisq.test(college.table) #the chisquare test

test_Example1

## 
##  Pearson's Chi-squared test
## 
## data:  college.table
## X-squared = 45.283, df = 2, p-value = 1.469e-10

test_Example1$expected

##          [,1]  [,2]    [,3]
## Premed  5.124  7.32 109.556
## Others 15.876 22.68 339.444

Example 2

prof_Bus=c(55, 38, 7)
skilled= c(79,71,25)
unskilled= c(22, 75, 3)
farmer=c(15,23,10,32)

career.table=rbind(prof_Bus, skilled, unskilled, farmer)#make a table

## Warning in rbind(prof_Bus, skilled, unskilled, farmer): number of columns of
## result is not a multiple of vector length (arg 1)

print(career.table) #not necessary  

##           [,1] [,2] [,3] [,4]
## prof_Bus    55   38    7   55
## skilled     79   71   25   79
## unskilled   22   75    3   22
## farmer      15   23   10   32

test_Example2=chisq.test(career.table) #the chisquare test

test_Example2

## 
##  Pearson's Chi-squared test
## 
## data:  career.table
## X-squared = 65.893, df = 9, p-value = 9.667e-11

test_Example2$expected

##               [,1]     [,2]     [,3]     [,4]
## prof_Bus  43.37971 52.51227 11.41571 47.69231
## skilled   71.08674 86.05237 18.70704 78.15385
## unskilled 34.14403 41.33224  8.98527 37.53846
## farmer    22.38953 27.10311  5.89198 24.61538

Example 3

centerA=c(50, 26,24)
centerB=c(40,34,26)
centerC=c(40, 20, 40)

center.table=rbind(centerA, centerB, centerC)#make a table
print(center.table) #not necessary  

##         [,1] [,2] [,3]
## centerA   50   26   24
## centerB   40   34   26
## centerC   40   20   40

test_Example2=chisq.test(center.table) #the chisquare test

test_Example2

## 
##  Pearson's Chi-squared test
## 
## data:  center.table
## X-squared = 10.305, df = 4, p-value = 0.03559

test_Example2$expected

##             [,1]     [,2] [,3]
## centerA 43.33333 26.66667   30
## centerB 43.33333 26.66667   30
## centerC 43.33333 26.66667   30

Example 4

Lab3_data=read.csv("Lab3Data.csv")

# make two way table
a=table(Lab3_data$HUNVFlag,Lab3_data$Urban)
rownames(a)=c("Sufficient access", "Not sufficient access")
colnames(a)=c("Non-urban", "Urban")
a

##                        
##                         Non-urban Urban
##   Sufficient access           410   707
##   Not sufficient access        54   336

b=prop.table(a,2)
barplot(b, beside=TRUE, legend=T, col=c("green","red"), main="Food access in urban and non-urban setting") 

test_Example4=chisq.test(a) #the chisquare test
test_Example4

## 
##  Pearson's Chi-squared test with Yates' continuity correction
## 
## data:  a
## X-squared = 69.816, df = 1, p-value < 2.2e-16

test_Example4$expected

##                        
##                         Non-urban    Urban
##   Sufficient access      343.9204 773.0796
##   Not sufficient access  120.0796 269.9204

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