Intro Stuff

library(tidyverse)
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library(infer)
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library(openintro)
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## Loading required package: airports
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getwd()
## [1] "C:/Users/Jerome/Documents/From_Toshiba_HD_Work_Files/0000_Montgomery_College/Math_217/Week_10"

Problem 9.4.5 -

NB: After example 9.4.4 in my text, there is a computational note that says chi-square must use absolute values, not relative values, for the observed. But in this problem, there are no expected absolutes, so I used the percentage for both expected and absolute. Was this wrong? Had I used absolute for observed, what would I have done for the expected?

chickmatrix<-matrix(c(0.584, 0.5625, 0.195, 0.1875,0.179, 0.1875, 0.042, 0.0625),ncol=2,byrow=TRUE)
rownames(chickmatrix)<-c("wfsc","wflc","dfsc","dflc")
colnames(chickmatrix)<-c("observed","expected")
chickmatrix <- as.table(chickmatrix)
chickmatrix
##      observed expected
## wfsc   0.5840   0.5625
## wflc   0.1950   0.1875
## dfsc   0.1790   0.1875
## dflc   0.0420   0.0625
# Now set the probability values for the expected proportions of chicks)
null.probs = c(9/16, 3/16, 3/16, 1/16)
chickdist = c(111, 37, 34, 8)
chisq.test(chickdist, p=null.probs) # p is not the second option, so must be labeled
## 
##  Chi-squared test for given probabilities
## 
## data:  chickdist
## X-squared = 1.5509, df = 3, p-value = 0.6706

10.3.3 (b)

died <-c(83, 106)
lived <- c(264, 262)
test <- data.frame(died, lived)
chisq.test(test)
## 
##  Pearson's Chi-squared test with Yates' continuity correction
## 
## data:  test
## X-squared = 1.9476, df = 1, p-value = 0.1628