STATISTICS
Paper details:
PBHLB300Homework #2
1. The social networking site called Facebook has grown quickly since its inception in 2004. In fact, Facebook’s
United States user base grew from 42 million users to 103 million users between 2009 and 2010. The table below
shows the age distribution of Facebook users (in thousands) as it changed from January 2009 to January 2010.
Age As of 1/04/2009 As of 1/04/2010
1317 5675 10,680
1824 17,192 26,ÕÉ≠†Њ†076
2534 11,255 25,580
3554 6989 29,918
55+ 955 9764
Unknown 23 1068
Total42,089 103,086
(a) Define the variable that has been measured in this table
(b) Is the variable quantitative or categorical?
(c) What do the numbers in each cell represent?
(d) Construct a pie chart to describe the age distribution of Facebook users as of January 2009.
(e) Construct a pie chart to describe the age distribution of Facebook users as of January 2010.
(f) Refer to parts (4) and (5). How would you describe the changes in the age distribution of Facebook users
during this 1year period?
2. People with diabetes must monitor and control their blood glucose level. The goal is to maintain “fasting
plasma glucose” between about 90 and 130 milligrams per deciliter (mg/dL).
(a) 18 diabetics enrolled in a diabetes control class. Their fasting plasma glucose levels at 5 months after the
end of the class are shown below:
141 158 112 153 134 95 96 78 148
172 200 271 103 172 359 145 147 255
Make a stemplot of these data and describe the main features of the distribution. (You may want to trim and also
split the stems remember, you can use the hundreds place as the stem, and tens as a leaf…). Are there
outliers? How well is the group as a whole achieving the goal for controlling glucose levels?
(b) The study also recruited 16 diabetics who were given individual instruction on diabetes control. Their fasting
plasma glucose levels are shown below:
128 195 188 158 227 198 163 164
159 128 283 226 223 221 220 160
Make a backtoback stemplot to compare the class and individual instruction groups. How do the distribution
shapes and success in achieving glucose control goal compare?
3. Creactive protein (CRP) can be measured in the blood. Values increase substantially within 6 hours of an
infection and reach a peak within 24 to 48 hours after. In adults, chronically high values have been linked to an
increased risk of cardiovascular disease. In a study of apparently healthy children aged 6 to 60 months in Papua
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New Guinea, CRP was measured in 90 children. The units are milligrams per liter (mg/l). Here are the data from a
random sample of 40 of these children.
0.00 3.90 5.64 8.22 0.00 5.62 3.92 6.81 30.61 0.00
73.20 0.00 46.70 0.00 0.00 26.41 22.82 0.00 0.00 3.49
0.00 0.00 4.81 9.57 5.36 0.00 5.66 0.00 59.76 12.38
15.74 0.00 0.00 0.00 0.00 9.37 20.78 7.10 7.89 5.53
(a) Find the 5number summary for these data. Calculate by hand.
(b) Are there any outliers?
(c) Make a boxplot.
(d) Make a histogram.
(e) Write a short summary of the major features of this distribution. Do you prefer the boxplot or the histogram
for the dat
