Chapter 4 Describing Your Data 175
Exercises
- Defi ne the following terms:
a. Quantitative variable
b. Qualitative variable
c. Continuous variable
d. Ordinal variable
e. Nominal variable
- What is a skewed distribution? What is pos-
itive skewness? What is negative skewness?
- What is a stem and leaf plot? What are the
advantages of stem and leaf plots over histo-
grams? What are some of the disadvantages?
- What is the interquartile range?
- True or false (and why): Distributions
with the same range have approximately
the same variability.
- What are outliers? What is considered a
moderate outlier? What is considered an
extreme outlier?
- True or false (and why): Outliers should
be removed from a data set before calcu-
lating statistics on that data set.
- What is a boxplot? What are the advan-
tages of boxplots over histograms? What
are some of the disadvantages?
- You see the following stem and leaf plot
in a technical journal:
Stem 3 100 | Leaf
0 | 336
1 | 01228
2 | 00111249
3 | 04
4 | 5
5 |
6 | 1
7 |
8 |
9 | 0
a. What are the approximate values of
the data set?
b. Is the distribution positively skewed,
negatively skewed, or symmetric?
c. Give approximate values for the mean
and the median.
d. What values, if any, appear to be
moderate and extreme outliers in the
distribution?
- A data distribution has a median value
of 22, a fi rst-quartile value of 20, and a
third-quartile value of 30. Five observa-
tions lie outside the interval from the
fi rst to the third quartile, with values of
17, 18, 40, 50, and 75.
a. Draw the boxplot for this distribution.
b. Is the skewness positive, negative, or
zero?
- You’re asked to do further research on
the housing market in Albuquerque,
New Mexico, during the early 1990s. In
this analysis you’ll examine the size of
the homes sold on the market and the
price per square foot of each home.
a. Open the Housing workbook from the
Chapter04 folder and save it as Home
Sizes.
b. Create a table of univariate statistics
for the size of the homes in square
feet, including all distribution, vari-
ability, and summary statistics except
the mode. Place the table on a work-
sheet named Sq Ft. Stats.
c. What are the smallest and largest
houses in the sample?
d. If you were interested only in houses
that were 2,200 square feet or higher,
what percentage of the houses in
the sample would meet the require-
ment? (Hint: Use the PERCENTRANK
function.)
