DATA, VARIABLES, AND CONCEPTS

READINGS

• Pollock, Essentials, preface, introduction, and ch. 1

• Course Reader, Selection 1 (Smith, Cycles of Electoral Democracy)

OUTLINE: THE PROCESS OF MEASUREMENT

• The Analytical Challenge: Uncovering Relationships between Concepts

• Stage I: Defining Concepts

• Stage II: Operationalizing Concepts

• Stage III: Variables and Levels of Measurement [next time]

PRIMARY GOALS OF POLITICAL SCIENCE:

Describing concepts and analyzing relationships between them. (Example: Degrees of democracy in Latin America and levels of economic development.)

A KEY CHALLENGE IN POLITICAL SCIENCE:

Translating abstract concepts into concrete terms—to express vague ideas in such as way that they can be described and analyzed.

STAGE ONE: DEFINING CONCEPTS

(a)Identifying the concept—i.e., the topic of research (e.g., democracy, justice, competition, religiosity)

(b) Providing a conceptual definition—clearly describing the properties of the concept

DEFINING CONCEPTS

1. Think of polar opposites2. Select most significant attributes

TEMPLATE:

The concept of ______ is defined as the extent to which ________ exhibit the characteristic of __________.

EXAMPLE:

The concept of religiosity is defined as the extent to which individuals exhibit the characteristic of attending religious services.

ON UNITS OF ANALYSIS:

Unit of analysis = the entity (person, city, country, bureaucracy, etc.) we want to describe and analyze

Individual-level unit of analysis deals with individuals;Aggregate-level unit of analysis deals with collections of individuals

Beware the ecological fallacy!

arising from use of aggregate-level phenomena to makeinferences at the individual level. (Example: left-wing votes in upper-class neighborhoods.)

STAGE TWO: OPERATIONAL DEFINITIONS

(a) Creating an operational definition—proposing the instrument to be used in measuring the conceptual definition, putting it “into operation”(b) Producing variables—which record the actual measurement of the concept.

An operational definition describes how the concept is to be measured empirically.

Validity is the degree to which the operational definition measures the characteristic described in the conceptual definition, and only that characteristic.

Reliability is the extent to which the operational definition is a consistent measure of the concept—i.e., containing no random error.

COMPONENTS OF MEASUREMENT:

Measurement = Intended characteristic

+ Systematic error

+ Random Error

ASSESSING VALIDITY

•Face validity

•Construct validity (does it behave the way it “should”?)

ASSESSING CONCEPT VALIDITY I:

Party % Engaging inIdentification Campaign Activity

Strong Democrat 53Weak Democrat 34Independent/Democrat 43Independent 28Independent/Republican 47Weak Republican 43Strong Republican 57

ASSESSING CONCEPT VALIDITY II: SCIENCE AND BASEBALL

Question: What’s the most accurate measure of effectiveness?

Conventional wisdom: Batting average, Slugging average, Stolen bases

Revised view:

On-base percentage (including walks as well as hits)

OPS: On-base plus slugging

“Runs Created” = (Hits + Walks) x Total Bases/(At Bats + Walks)