## Statistics 2MA3 - Exercise #1

### 2003-01-08

####

"Never on Sunday"

Every morning from 1993-11-16 to 1995-01-19, I recorded the price
per litre of regular gasoline at Sarah's Sunoco on Main Street West
at Newton Avenue and at the Petro Canada station on Main Street West
at Longwood Road. Click here to get the
data.

Use R to plot the following graphs. Paste the graphs into MS Word,
then add captions and some discussion to make a short report on the
data.

- Make a scatter plot of the daily Sunoco prices against the
daily Petro Canada prices.
- Draw a lag -1 scatter plot of the Sunoco data; that is, plot today's price on the Y-axis against yesterday's price on the X-axis, for each day. (A lag +1 plot would plot yesterday's price on the Y-axis against today's price on the X-axis and would also be acceptable.)
- Give a comparative box plot showing the Sunoco price against
day of the week.
- If x(i) is the Sunoco price on day i, compute d(i) = x(i+1) -
x(i), i.e. the change in price that occurred on day i. Draw a
comparative box plot showing change in price against day of the
week.
- Display the Sunoco change in price on a histogram.
- Display the Sunoco change in price on a stem-and-leaf diagram.
- Display the Sunoco price on a time sequence plot.
- Display the Sunoco change in price on a time sequence plot.
- Plot change in price against price, for the Sunoco data.
- Can you think of any other graphs that would help to interpret
these data?
- Explain what you have learned from each graphical display. Why
did I call this "Never on Sunday"?