1. CH. 8 MEASUREMENT OF VARIABLES: OPERATIONAL DEFINITION AND SCALES

2. 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

3. 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.

4. 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.

5. Operational Definition: Dimensions and Elements
Concepts
Dimensions
Elements

6. Operational Definition: Dimensions and Elements (Cont’d)

7. 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

8. 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

9. Types of Scales Nominal Ordinal Interval Ratio
Students will be building their measurement questions from different types of scales. They need to know the difference in order to choose the appropriate type. Each scale type has its own characteristics.
Ratio

10. Levels of Measurement Classification Nominal Ordinal Interval Ratio
This is a good time to ask students to develop a question they could ask that would provide only classification of the person answering it.
Classification means that numbers are used to group or sort responses.
Consider asking students if a number of anything is always an indication of ratio data. For example, what if we ask people how many cookies they eat a day? What if a business calls themselves the “number 1” pizza in town? These questions lead up to the next slide. Does the fact that James wears 23 mean he shoots better or plays better defense than the player donning jersey number 18?
Ratio

11. 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).

12. Levels of Measurement Classification Nominal Classification Ordinal
Order
Interval
Order means that the numbers are ordered. One number is greater than, less than, or equal to another number.
You can ask students to develop a question that allows them to order the responses as well as group them. This is the perfect place to talk about the possible confusion that may exist when people order objects but the order may be the only consistent criteria. For instance, if two people tell them that Pizza Hut is better than Papa Johns, they are not necessarily thinking precisely the same. One could really favor Pizza Hut and never considering eating another Papa John’s pizza, which another could consider them almost interchangeable with only a slight preference for Pizza Hut. This discussion is a perfect lead in to the ever confusing ‘terror alert’ scale (shown on the next slide)…or the ‘weather warning’ system used in some states to keep drivers off the roads during poor weather. Students can probably come up with numerous other ordinal scales used in their environment.
Ratio

13. 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.

14. Levels of Measurement Nominal Classification Ordinal Classification
Order
Interval
Classification
Distance
Order
In measuring, one devises some mapping rule and then translates the observation of property indicants using this rule.
Mapping rules have four characteristics and these are named in the slide.
Classification means that numbers are used to group or sort responses.
Order means that the numbers are ordered. One number is greater than, less than, or equal to another number.
Distance means that differences between numbers can be measured.
Origin means that the number series has a unique origin indicated by the number zero.
Combinations of these characteristics provide four widely used classifications of measurement scales: nominal, ordinal, interval, and ratio.
Ratio

15. 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

16. Levels of Measurement Nominal Classification Ordinal Classification
Order
Interval
Classification
Distance
Order
In measuring, one devises some mapping rule and then translates the observation of property indicants using this rule.
Mapping rules have four characteristics and these are named in the slide.
Classification means that numbers are used to group or sort responses.
Order means that the numbers are ordered. One number is greater than, less than, or equal to another number.
Distance means that differences between numbers can be measured.
Origin means that the number series has a unique origin indicated by the number zero.
Combinations of these characteristics provide four widely used classifications of measurement scales: nominal, ordinal, interval, and ratio.
Ratio
Classification
Distance
Order
Natural Origin

17. 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.

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