CH. 8MEASUREMENT OF

VARIABLES: OPERATIONAL

DEFINITION AND SCALES

How Variables Are Measured

• Objects that can be physically measured by some calibrated instruments pose no measurement problems.

• Data representing several demographic characteristics are also easily obtained

• Certain things lend themselves to easy measurement through the use of appropriate measuring instruments

How Variables Are Measured (Cont’d)

• But the measurement of people’s subjective feelings, attitudes, and perceptions becomes difficult.

• Despite the lack of physical measuring devices, there are ways of tapping the subjective feelings and perceptions of individuals.

How Variables Are Measured (Cont’d)

• One technique is to reduce the abstract notions or concepts to observable behavior and characteristics.

• Reduction of abstract concepts to render them measurable in a tangible way is called operationalizing the concepts.

Operational Definition: Dimensions and Elements

• Concepts

• Dimensions

• Elements

Operational Definition: Dimensions and Elements (Cont’d)

What an Operational Definition is Not

• Operationally defining a concept does not consist of delineating the reasons, antecedents, consequences, or correlates of the concept.

• Rather, it describes its observable characteristics in order to be able to measure the concept

Scales• A scale is a tool or mechanism by which

individuals are distinguished as to how they differ from one another on the variables of interest to our study

Types of Scales

OrdinalOrdinal

IntervalInterval

RatioRatio

NominalNominal

Levels of Measurement

OrdinalOrdinal

IntervalInterval

RatioRatio

NominalNominal ClassificationClassification

Nominal Scale

• A nominal scale is the one that allow the researcher to assign subjects to certain categories or groups.

• For example: gender (male and female).

Levels of Measurement

OrdinalOrdinal

IntervalInterval

RatioRatio

NominalNominal ClassificationClassification

OrderOrderClassificationClassification

Ordinal Scale

• An ordinal scale not only categorizes the variables in such a way as to denote difference among the various categories, it also rank-orders the categories in some meaningful way.

• For example: indicate the preferences by ranking the importance of several distinct characteristics

• Ordinal scale does not give any indication of the magnitude of the differences among the ranks.

Levels of Measurement

OrdinalOrdinal

IntervalInterval

RatioRatio

NominalNominal ClassificationClassification

OrderOrderClassificationClassification

OrderOrderClassificationClassification DistanceDistance

Interval Scale

• An interval scale allows us to perform certain mathematical operations on the data collected from respondents.

• Characteristics of nominal and ordinal scales plus the concept of equality of interval.

• Equal distance exists between numbers• The origin could be any arbitrary number

Levels of Measurement

OrdinalOrdinal

IntervalInterval

RatioRatio

NominalNominal ClassificationClassification

OrderOrderClassificationClassification

OrderOrderClassificationClassification DistanceDistance

Natural OriginNatural Origin

OrderOrderClassificationClassification DistanceDistance

Ratio Scale

• The ratio scale overcomes the disadvantage of the arbitrary origin point of the interval scale, in that it has an absolute zero point, which is a meaningful measurement point.

• It is the most powerful of the four scales.

Scales

• Whenever it is possible to use a more powerful scale than a less one, it is wise to do so.