DownstateTalk

Chunk where you install and/or load all necessary packages

Vitamin C example’s contingency table and chi-square test

ski.reg<-matrix(c(31, 17, 109, 122), ncol=2, dimnames=list(Treatment=c("Placebo", "VitaminC"), Cold=c("Cold", "NoCold")))
ski.reg %>%
  kbl(caption = "French Skiers Regular") %>%
  kable_classic(full_width = F, html_font = "Cambria")

French Skiers Regular

	Cold	NoCold
Placebo	31	109
VitaminC	17	122

result.reg<-chisq.test(ski.reg, correct = FALSE) # without CC
result.reg

## 
##  Pearson's Chi-squared test
## 
## data:  ski.reg
## X-squared = 4.8114, df = 1, p-value = 0.02827

Deflated Version

ski.deflate<-matrix(c(3, 2, 11, 12), ncol=2, dimnames=list(Treatment=c("Placebo", "VitaminC"), Cold=c("Cold", "NoCold")))
ski.deflate %>%
  kbl(caption = "French Skiers Deflated") %>%
  kable_classic(full_width = F, html_font = "Cambria")

French Skiers Deflated

	Cold	NoCold
Placebo	3	11
VitaminC	2	12

result.def<-chisq.test(ski.deflate, correct = FALSE) # without CC
result.def

## 
##  Pearson's Chi-squared test
## 
## data:  ski.deflate
## X-squared = 0.24348, df = 1, p-value = 0.6217

Inflated Vesrion

ski.inflate<-matrix(c(310, 170, 1090, 1220), ncol=2, dimnames=list(Treatment=c("Placebo", "VitaminC"), Cold=c("Cold", "NoCold")))
ski.inflate %>%
  kbl(caption = "French Skiers Inflated") %>%
  kable_classic(full_width = F, html_font = "Cambria")

French Skiers Inflated

	Cold	NoCold
Placebo	310	1090
VitaminC	170	1220

### Pearson's Chi-squared test  with Yates' continuity correction
result.inf<-chisq.test(ski.inflate, correct = FALSE)
result.inf

## 
##  Pearson's Chi-squared test
## 
## data:  ski.inflate
## X-squared = 48.114, df = 1, p-value = 4.021e-12