Question

please answer the following question using r studio and provide screen shots.

download the data and import them into RStudio as a dataframe using read.csv(), or impor them directly using the following code:

# install.packages('RCurl') # uncomment and run this line if RCurl not installed

library(RCurl) # makes getURL() function available

u <- 'https://docs.google.com/spreadsheets/d/1ZbIMHRP9mZnDS4WIiAt1Wk8dsQBQjCE0oTXWLv13fOA/pub?gid=1142643825&single=true&output=csv'

tc <- getURL(u, ssl.verifypeer=FALSE)

practice <- read.csv(textConnection(tc))

Then, using the function mean(), answer the following question:

1.What are the mean Before and After scores?

Select one:

a. Before = 36.5 cm, After = 38.5 cm

b. Before = 33.75 cm, Output = 33.75 cm

c. Before = 37.52 cm, After = 31.27 cm

d. Before = 29.3 cm, After = 33.2 cm

2.What is the 95% confidence interval for the mean improvement? Hint: calculated a 95% CI on the data in the improvement column.

Select one:

a. (0.875 cm, 5.00 cm)

b. (6.63 cm, 11.7 cm)

c. (4.537 cm, 7.952 cm)

d. (4.54 cm, 7.95 cm)

Answer 1

1. What are the mean Before and After scores?

From the given data,

Mean Before = 18234.72/486 = 37.52

Mean After = 15197.22/486 = 31.27

Before = 37.52 cm, After = 31.27 cm

2. What is the 95% confidence interval for the mean improvement?

From the given data n= 486,

Z = 1.96

X-bar = 6.19

Confidence interval for the mean improvement = (4.54 cm, 7.95 cm)