stat 540 question
Point values are shown in parentheses; 35 points total
1. (10 points). The data set XYdata.csv posted on Bb were collected in petri dishes, with each
dish having a given concentration of Cadmium Chloride (X, micrograms/liter) in solution, and
the growth of algae cells Y (cells x 10^4/ml) in the was dish recorded after two weeks’ time.
Input the data into R, creating a data frame. Provide me the commands you used and issue ls()
to check that it’s there. Then construct a scatter plot of the data (X on the horizontal axis), with
a title and well-labeled axes (include units of measurement somewhere on the plot). Include
your name in the title. Then, add a smooth fitted quadratic curve given by the equation
Make sure that all the points and the entire curve fit on the plot. Provide me the commands
you used to construct your final graph, as well the graph itself.
2. (10 points) The Statistics department’s distance-ed headcount enrollments by term (three
terms per year – FA, SP, SU etc.) from Fall 1999 through Fall 2004 were:
2, 1, 0, 4, 10, 3, 9, 8, 0, 9, 10, 6, 20, 23, 8, 23.
Get this data into R as a numeric vector (type it carefully using c()). Then, use the data to
construct a graph like the one at the top of the next page, except include your name in the title.
Hint: look for the names.arg argument in help(barplot). Also, look at help(legend) to place the
text in a box at top left in the graph. Give me the commands you used and the graph itself. The
color need not match exactly, but the legend should be two lines at top left of the graph.
STAT 540 Hwk 2 p.1
3. (15 points) Issue the command >data(WorldPhones) and then inspect the loaded data. Then,
construct a graph as similar to the one shown below as you can; use your name in the title.
Provide me the commands you used and the graph itself. Hint: under help(lines), look for the
option type. Also, see help(legend). Note that the plot starts in 1956, though the first row of
the raw data is 1951.
STAT 540 Hwk 2 p.2
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