Statistics for the Behavioral Sciences by Frederick J. Gravetter, Larry B. Wallnau ISBN 10: 1305504917 ISBN 13: 9781305504912

SECTION 3.5 | Selecting a Measure of Central Tendency 91
160
Median
new
house
cost
(in $1000s)
125
100
75
50
FIGURE 3.10
Median cost of a new,
single-family home by
region.
25
Northeast South Midwest
Region of the United States
West
When constructing graphs of any type, you should recall the basic rules we introduced
in Chapter 2:
1. The height of a graph should be approximately two-thirds to three-quarters of its
length.
2. Normally, you start numbering both the X-axis and the Y-axis with zero at the point
where the two axes intersect. However, when a value of zero is part of the data, it is
common to move the zero point away from the intersection so that the graph does
not overlap the axes (see Figure 3.9).
Following these rules will help produce a graph that provides an accurate presentation
of the information in a set of data. Although it is possible to construct graphs that distort
the results of a study (see Box 2.1), researchers have an ethical responsibility to present an
honest and accurate report of their research results.
LEARNING CHECK
1. A teacher gave a reading test to a class of 5th-grade students and computed the
mean, median, and mode for the test scores. Which of the following statements
cannot be an accurate description of the scores?
a. The majority of the students had scores above the mean.
b. The majority of the students had scores above the median.
c. The majority of the students had scores above the mode.
d. All of the other options are false statements.
2. One item on a questionnaire asks, “How many siblings (brothers and sisters) did you
have when you were a child?” A researcher computes the mean, the median, and the
mode for a set of n 5 50 responses to this question. Which of the following statements
accurately describes the measures of central tendency?
a. Because the scores are all whole numbers, the mean will be a whole number.
b. Because the scores are all whole numbers, the median will be a whole number.
c. Because the scores are all whole numbers, the mode will be a whole number.
d. All of the other options are correct descriptions.