1
Overview
Why Scale Development??
1. No Existing Scales
2. Existing Scales are Inappropriate
3. Secondary Data Analysis
Measurement is a fundamental activity of science
What is Measurement?

The assignment of numbers to categories of observations

A way to provide a reasonable and consistent way to summarize responses people make
to express their achievements, attitudes, or personal points of view through instruments
such as scales, tests, questionnaires, surveys, and psychological scales.

Haphazard measurement approaches lead to inaccurate research results due to faulty data
The Relationship between Theory and Measurement

The phenomena we try to measure in social science research is often derived from theory,
so theory plays a key role in how we conceptualize our measurement problems

Theory in the social sciences differs from theory in the physical sciences in the following
ways:
Social Sciences
Numerous theoretical models
Models concern fairly narrow
phenomena
Less Mature
Physical Sciences
Fewer theoretical models
Models concern fairly
comprehensive phenomena
More Mature
 Measuring elusive intangible phenomena derived from multiple competing theories poses
a clear challenge to researchers!
 The more researchers know about the:
1. Phenomena they are interested in
2.
Abstract relationships that exist among hypothetical constructs
3.
Quantitative tools available
The more likely they will develop reliable, valid, and useful scales

Different measures capturing distinct aspects of the same general phenomena may not
yield the same results.
2

Measures may be assessing different variables, despite the use of a common variable
name.

Developing a measure that is optimally suited to the research question requires
understanding the subtleties of the theory
The focus of this course is on developing measures/scales/instruments that
differentiate between different levels of some underlying theoretical
construct, not all self report surveys are theoretical
Examples:

Sex and Age: Depending on the research question these two variables could be
components of a theoretical model or they could simply be part of the description of
participants of a study

Public Opinion Questionnaires: The focus on these types of surveys is in the responses to
the items, not in some characteristic of the person

Sometimes a study may be conducted to formulate a theory (i.e. patterns of consumer
spending)

Other times, distinguishing between theoretical and non-theoretical measurement
situations may not be so clear cut (e.g. Voters preference to predict the outcome of an
election, as opposed to voter preference in the context of attitudes toward specific issues).

Whether or not theory is used in developing a measure is sometimes a matter of the
researcher’s intent, not the procedures used.

Measurement instruments that are collections of items combined into a composite score,
intended to reveal levels of theoretical variables that are not readily observable by direct
means are often referred to as scales. Although observational techniques may be used to
differentiate between levels of theoretical variables, often times this is not practical.

Not all phenomena require multi-item scales (i.e. age and gender), some phenomena are
routinely measured using a single item (i.e. ethnicity) which may or may not be
appropriate, other times only a scale will allow a researcher to get at the complexity of
the phenomenon of interest.

A scale can be thought of as a collection of effect indicators, or items for which values
depend on an underlying construct or latent variable

An index, on the other hand, can be thought of as a collection of cause indicators, or
items that determine the value of a construct. An example of this might be a measure of
presidential candidate appeal. The items might assess geographical residence, family
size, physical attractiveness, ability to inspire, stance on important political topics (i.e.
taxes, education, abortion), and financial resources. Although these items are not the
result of any one thing, together they determine the same outcome.

A more general term for a collection of items that one might group together is emergent
variable. In this case there is neither a common cause nor a common consequence.
3
Construct Modeling

The approach we will be taking in this class is based on the idea that there is a single
underlying characteristic that a scale is designed to measure, although the construct itself
is composed of multiple characteristics.

It will be assumed that we can consider each of the multiple characteristics independently
such that the final instrument is composed of several scales, each measuring a single
characteristic.

A construct can be considered to be part of a theoretical model of a person’s cognition.
Examples include personality, quality of life, migrants’ degree of assimilation, selfesteem, and health literacy.

It will be assumed that the construct being measured has a particularly simple form, such
that it extends from one extreme to another - from high to low, small to large, positive to
negative, or strong to weak.

It is further assumed that the underlying construct is continuous and that respondents can
lie at any point in between the two extremes. The purpose of measurement is to
determine where a respondent stands on this range from one extreme to the other.

The following diagram illustrates the scale development cycle:
Construct
Map
Measures
Items
Item
Scores