Chapter 12 - Measurement: Scaling, Reiability and Validity
Learning Objectives:
1. Describe the characteristics and power of the four types of scales - nominal,
ordinal, interval, and ratio.
2. Describe and know how and when to use different forms of rating scales
3. Describe and know how and when to use different forms of ranking scales
4. Discuss international dimensions of scaling.
5. Describe validity and reliability and how they are established and assess the
reliability and validity of a scale.
6. Explain the difference between reflective and formative scales.
Introduction
We explained that measurement is the assignment of numbers or other symbols to
characteristics of objects according to a prespecified set of rules. Now that we have learned
how to operationally define a concept, we need to assign numbers to it in some manner.
Numbers allow us to perform statistical analysis on the resulting data and to test the
hypothesis that we have developed.
Four types of 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. Scaling involves the creation of a
continuum on which our objects are located. Suppose that we want to measure consumer
attitudes towards soft drink consumption. After we have developed one or more scale items
or questions, the next step in measurement is to decide on a scale that allows us to assign
to the attribute of our objects. This allows us to subsequently classify the consumers in terms
of how unfavorable or favorable they are toward drinking a soft drink. One of our options is a
Linker Scale. Which is a 5 point scale with 1 being strongly agree and 5 being strongly
disagree. There are four basic types of scales: nominal, ordinal, interval, and ratio. The
degree of sophistication to which the scales are fine-tuned increases progressively as we
move from the nominal to the ratio scale.
Nominal Scale
A nominal scale is one that allows the researcher to assign subjects to certain categories or
groups. For example, respondents can be grouped into two categories - male and female.
These two groups can be assigned code numbers 1 and 2. These numbers serve as simple
and convenient category labels with no intrinsic value, other than to assign respondents to
one of two nonoverlapping, or mutually exclusive, categories. There is also no third category
into which respondents would normally fall. Thus, the nominal scale gives us some basic,
categorical, gross information.
Ordinal Scale
An ordinal scale not only categorizes the variables in such a way as to denote differences
among the various categories, but it also rank-orders the categories in some meaningful
way. The ordinal scale provides more information than the nominal scale. The ordinal scale
goes beyond differentiating the categories to providing information on how respondents
distinguish them by rank-ordering them. However, the ordinal scale does not give any
, indication of the magnitude of the differences among the ranks.
Interval Scaling
In an interval scale or equal interval scale, numerically equal distances on the scale
represent equal value in the characteristics being measured. The interval scale, taps the
differences, the order, and the equality of the magnitude of the differences in the variable. As
such, it is a more powerful scale than the nominal and ordinal scales and has for its measure
of central tendency the arithmetic mean. Its measures of dispersion are the range, the
standard deviation, and the variance.
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. Thus, the
ratio scale not only measures the magnitude of the differences between points on the scale
but also taps the proportions in the differences. It is the most powerful of the four scales
because it has a unique zero origin and subsumes all the properties of the other three
scales. The measure of central tendency of the ratio scale may be either the arithmetic or
the geometric mean and the measure of dispersion may be either the standard deviation, or
variance, or the coefficient of variation.
Ordinal or Interval?
Likert Scales are a commonly used way of measuring opinions and attitudes. They measure
the extent to which participants agree or disagree with a given statement and typically range
from 1 to 5 with a neutral point in the middle.
Review of Scales
The four scales that can be applied to the measurement of variables are nominal, ordinal,
interval, and ratio scales. The nominal scale highlights the differences by classifying objects
or persons into groups and provides the least amount of information on the variable. The
ordinal scale provides some additional information by rank-ordering the categories of the
nominal scale. The interval scale not only ranks but also provides us with information on the
magnitude of the differences in the variable. The ratio scale indicates not only the magnitude
Learning Objectives:
1. Describe the characteristics and power of the four types of scales - nominal,
ordinal, interval, and ratio.
2. Describe and know how and when to use different forms of rating scales
3. Describe and know how and when to use different forms of ranking scales
4. Discuss international dimensions of scaling.
5. Describe validity and reliability and how they are established and assess the
reliability and validity of a scale.
6. Explain the difference between reflective and formative scales.
Introduction
We explained that measurement is the assignment of numbers or other symbols to
characteristics of objects according to a prespecified set of rules. Now that we have learned
how to operationally define a concept, we need to assign numbers to it in some manner.
Numbers allow us to perform statistical analysis on the resulting data and to test the
hypothesis that we have developed.
Four types of 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. Scaling involves the creation of a
continuum on which our objects are located. Suppose that we want to measure consumer
attitudes towards soft drink consumption. After we have developed one or more scale items
or questions, the next step in measurement is to decide on a scale that allows us to assign
to the attribute of our objects. This allows us to subsequently classify the consumers in terms
of how unfavorable or favorable they are toward drinking a soft drink. One of our options is a
Linker Scale. Which is a 5 point scale with 1 being strongly agree and 5 being strongly
disagree. There are four basic types of scales: nominal, ordinal, interval, and ratio. The
degree of sophistication to which the scales are fine-tuned increases progressively as we
move from the nominal to the ratio scale.
Nominal Scale
A nominal scale is one that allows the researcher to assign subjects to certain categories or
groups. For example, respondents can be grouped into two categories - male and female.
These two groups can be assigned code numbers 1 and 2. These numbers serve as simple
and convenient category labels with no intrinsic value, other than to assign respondents to
one of two nonoverlapping, or mutually exclusive, categories. There is also no third category
into which respondents would normally fall. Thus, the nominal scale gives us some basic,
categorical, gross information.
Ordinal Scale
An ordinal scale not only categorizes the variables in such a way as to denote differences
among the various categories, but it also rank-orders the categories in some meaningful
way. The ordinal scale provides more information than the nominal scale. The ordinal scale
goes beyond differentiating the categories to providing information on how respondents
distinguish them by rank-ordering them. However, the ordinal scale does not give any
, indication of the magnitude of the differences among the ranks.
Interval Scaling
In an interval scale or equal interval scale, numerically equal distances on the scale
represent equal value in the characteristics being measured. The interval scale, taps the
differences, the order, and the equality of the magnitude of the differences in the variable. As
such, it is a more powerful scale than the nominal and ordinal scales and has for its measure
of central tendency the arithmetic mean. Its measures of dispersion are the range, the
standard deviation, and the variance.
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. Thus, the
ratio scale not only measures the magnitude of the differences between points on the scale
but also taps the proportions in the differences. It is the most powerful of the four scales
because it has a unique zero origin and subsumes all the properties of the other three
scales. The measure of central tendency of the ratio scale may be either the arithmetic or
the geometric mean and the measure of dispersion may be either the standard deviation, or
variance, or the coefficient of variation.
Ordinal or Interval?
Likert Scales are a commonly used way of measuring opinions and attitudes. They measure
the extent to which participants agree or disagree with a given statement and typically range
from 1 to 5 with a neutral point in the middle.
Review of Scales
The four scales that can be applied to the measurement of variables are nominal, ordinal,
interval, and ratio scales. The nominal scale highlights the differences by classifying objects
or persons into groups and provides the least amount of information on the variable. The
ordinal scale provides some additional information by rank-ordering the categories of the
nominal scale. The interval scale not only ranks but also provides us with information on the
magnitude of the differences in the variable. The ratio scale indicates not only the magnitude
