Week4

R Markdown

This is an R Markdown document. Markdown is a simple formatting syntax for authoring HTML, PDF, and MS Word documents. For more details on using R Markdown see http://rmarkdown.rstudio.com.

When you click the Knit button a document will be generated that includes both content as well as the output of any embedded R code chunks within the document. You can embed an R code chunk like this:

summary(cars)

##      speed           dist       
##  Min.   : 4.0   Min.   :  2.00  
##  1st Qu.:12.0   1st Qu.: 26.00  
##  Median :15.0   Median : 36.00  
##  Mean   :15.4   Mean   : 42.98  
##  3rd Qu.:19.0   3rd Qu.: 56.00  
##  Max.   :25.0   Max.   :120.00

Including Plots

You can also embed plots, for example:

Note that the echo = FALSE parameter was added to the code chunk to prevent printing of the R code that generated the plot.

data("ToothGrowth")
boxplot(ToothGrowth$len)

hist(ToothGrowth$len) 

#Q3: H0=17, H1>17
#Q4: 단측검정, 17 이상인지 확인한다.
#Q5: t-value, 표본 표준편차 사용
sample_mean<-mean(ToothGrowth$len)
sample_std_dev<-sd(ToothGrowth$len)
population_mean<-17
sample_size<-length(ToothGrowth$len)
t_value<-(sample_mean-population_mean)/(sample_std_dev/sqrt(sample_size))
P_value<-1-pt(t_value, df=sample_size-1)
P_value

## [1] 0.0356806

#Q8: P-value<0.05, 귀무가설 기각, 평균 이빨 길인는 17 이상이다.