520 Statistical Methods
- The Tornado workbook records the
number of tornadoes of various lev-
els of severity in Kansas from 1950 to
1999. Tornadoes are rated on the Fujita
Tornado Scale, which ranges from minor
tornadoes rated at F0 to major tornadoes
rated at F5. You’ve been asked to deter-
mine whether the number of tornadoes
has changed over this period of time.
a. Open the Tornado workbook from
the Chapter12 folder and save it as
Tornado Control Chart.
b. Create a C chart of the number of
tornadoes each year for each
severity level and then for all types of
tornadoes.
c. Which classes of tornadoes show
signs of being out of statistical con-
trol? Describe the problem.
d. Techniques in recording and counting
tornadoes have improved in the last
few decades, especially for minor
tornadoes. Explain how this fact may
be related to the results you noted in
part c.
e. Save your changes to the workbook
and report your results.