# read in Reading dataset
# either with Import dataset or read.csv()

fourthgr=read.csv('https://webpages.uidaho.edu/~renaes/Data/4threading.csv',
                  header=T)
attach(fourthgr)
# Make a histogram
hist(Speed,main="Histogram of Reading speed")
hist(Comp,main="Histogram of Reading comprehension",xlab="Comprehension")

# Summary statistics
# Basic descriptive statistics

# install.packages("pastecs")
library(pastecs)
stat.desc(Speed)
library(stargazer)
stargazer(fourthgr,type='text')


# or just use t.test with no mu specified (not needed for CI only)
# 95% CI
t.test(Speed)
# 90% Ci
t.test(Speed,conf.level=.90)
99% CI
t.test(Speed,conf.level=.99)

# hypothesis test:

# Reading speed in 4th graders is usually around 8.5 minutes.
# We took a random sample of 20 4th graders and the sample
# mean was 9.1 with standard deivation of 2.57. Is there sufficient
# evidence that the reading speed for these 4th graders is higher 
# than average (slower reading times)? (assume alpha = 0.05)

# H0: mu = 8.5  Ha: mu > 8.5
# assumptions: random (yes), independence (yes because random), roughly normal

mu0=8.5
t.test(Speed,mu=8.5,alternative='l') # for test
t.test(Speed) # for CI