Single Indicator &
Composite Measures
UAPP 702: Research Design for Urban & Public Policy
Based on notes by Steven W. Peuquet. Ph.D.
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Single Indicators
A single indicator is a device for assigning
units of observation to levels of a variable.
 Questions are commonly used as single
indicator devices.
 Questions used for this purpose allow the
respondent to categorize him or herself to
a specified level of a variable.
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Single Indicators
There are three types of questions that
produce single indicator measures.
Examples of each follow:
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Single Indicators
Example 1:
In the last 30 days, how many nights have
you slept at an emergency shelter located in
Delaware?
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Single Indicators
Explanation of Example 1:
This question asks the respondent to assign
him- or herself to a level of this variable
(which might be called “recent shelter use”).
This variable has the properties of a ratio
variable. (A person that has stayed in a
shelter 30 nights is twice as much as a
person who has stayed 15 nights.)
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Single Indicators
Example 2:
For the last emergency shelter you stayed at,
how satisfied were you with the services
provided by that shelter?
1.
2.
3.
4.
5.
Very satisfied
Somewhat satisfied
Neutral (not satisfied or unsatisfied)
Somewhat unsatisfied
Very unsatisfied
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Single Indicators
Explanation of Example 2:
With this question you are asking
respondents to categorize themselves into
one of five categories. You are ordering them
on the basis of how satisfied or unsatisfied
they are. This variable has ordinal properties
because we don’t know how much more
satisfied a person who answers “very
satisfied” is compared to a person who
answers “somewhat satisfied.”
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Single Indicators
Example 3:
What race do you consider yourself to be?
1.
2.
3.
4.
African-American or Black
Caucasian or White
Asian or Oriental
Other
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Single Indicators
Explanation of Example 3:
This variable allows the respondent to
categorize him- or herself into one of four
categories (or levels) of this variable called
“race.” This variable has nominal values
because the responses cannot be averaged,
and one response can’t be considered to
have a higher rank than another response.
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Single Indicators vs.
Composite Measures
If the phenomenon that you are measuring is
more complex (like “prejudice” or “socioeconomic status” or “intelligence” or “historic
significance”) you may need to use a
composite measure. The function of a
single indicator is to assign units of analysis
to categories or levels of a variable. The
purpose of a composite measure is exactly
the same, but is used when a single indicator
won’t do the job.
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Composite Measures
 Composite measures are based on more
than one data item.
 There are two different types of composite
measures:
 Indices
 Scales
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Composite Measures
Both indices and scales are ordinal
measures of variables. The difference
between the two is based on how
scores are assigned.
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Composite Measures – Indices
An index is constructed through the
simple accumulation of scores
assigned to individual attributes. All
items are weighted the same.
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Composite Measures – Indices
Examples of an index:
 “Prejudice” might be measured by adding up the
number of prejudicial statements a person
agrees with.
 Assessing math skills through use of a multiple
choice exam. Asking just one question would not
be adequate. Several questions taken together
will do a better job of measuring how well the
student has acquired knowledge about the
subject matter.
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Composite Measures - Scales
A scale on the other hand is
constructed through the assignment of
scores to patterns of responses,
recognizing that some items reflect a
relatively weak degree of the variable,
while other reflect something stronger.
Scales take advantage of any intensity
structure that may exist among
attributes.
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Composite Measures – Scales
Examples of scales:

Essay or multiple choice exam where
different questions are worth different
amounts of points.

Hierarchy of political activity (voted,
contributed money to a campaign, worked on
a political campaign, ran for office)
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Composite Measures – Scales
Scales are generally superior to
indices because scales take into
consideration the intensity with
which different items reflect the
variable being measured.
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Composite Measures – Factors
to Consider in their Construction
 Face validity
 Unidimensionality (e.g., don’t mix
religion with political orientation)
 Amount of variance in responses
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Composite Measures – Factors
to Consider in their Construction
 Bi-variate and multi-variate relationship
between items (items should be related
to each other, but not perfectly related. If
items are not related, they are probably
measuring different things. If two items
are perfectly related, they are
redundant, and are not adding any new
information).
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Composite Measures – Factors
to Consider in their Construction
 “Index scoring” involves making
decisions about the range of the
index and the frequencies of
responses across the chosen range.
Once decided, the index is
calculated.
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Composite Measures – Factors
to Consider in their Construction
 Once created, a composite measure must be
validated. The basic question is: does the
index or scale actually measure the
phenomenon that is sought to be measured?
 “Item analysis” – examination of the extent to
which the index is related to (predicts responses
to) the individual items it comprises
 “External validation” – validating the index using
some other measure which is not part of the index
being evaluated
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Major Types of Scales
Bogardus Social Distance Scale – Increasing
intensity of the questions clearly shows a
pattern (e.g., Are you willing to let Albanians
live in your country, be your neighbor, marry
your son or daughter?).
Thurstone Scales – Use of “judges” to
determine the strength of each of several
indicators being used in a scale (e.g. figure
skating competition).
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Major Types of Scales
Likert Scales






3- point, 5-point or 7-point scale is common (example:
agree, neutral, disagree)
Odd number in scale is used so mid-point is a whole
number. Use of an even number of points on the scale
forces people to “take a stand” on one side of an issue or
the other.
Make questions as simple as possible
Use words respondents will understand
Don’t use double negatives
Don’t put more than one concept in a question
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Example of the Use
of a Composite Measure
The Use of the “Index of Dissimilarity”
to Measure Racial Residential Segregation
in New Castle County, Delaware
See example here
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