Keywords ;
Research Scales
Types of scales used in measuring
behavior
Nominal
Ordinal
Interval
Ratio
.
Types of scales used in measuring
behavior
The lowest measurement level you
can use, from a statistical point of view, is a nominal scale.
A nominal scale, as the name
implies, is simply some placing of data into categories, without any order or
structure.
In research activities a YES/NO
scale is nominal. It has no order and there is no distance between YES and NO.
The statistics which can be used
with nominal scales are in the non-parametric group. The most likely ones would
be:
Mode
cross tabulation - with chi-square
There are also highly
sophisticated modeling techniques available for nominal data.
.
Ordinal
An ordinal scale is next up the
list in terms of power of measurement.
The simplest ordinal scale is a
ranking. When a market researcher asks you to rank 5 types of ice creams from
most flavorful to least flavorful, he/she is asking you to create an ordinal
scale of preference.
There is no objective distance
between any two points on your subjective scale. For you the top ice cream may
be far superior to the second preferred ice cream but, to another respondent
with the same top and second beer, the distance may be subjectively small.
.
Ordinal data would use
non-parametric statistics. These would include:
Median and mode
rank order correlation
non-parametric analysis of variance
Modelling techniques can also be
used with ordinal data.
.
Interval
The standard survey rating scale
is an interval scale.
When you are asked to rate your
satisfaction with a piece of software on a 7 point scale, from Dissatisfied to
Satisfied, you are using an interval scale.
It is an interval scale because it
is assumed to have central points between each of the scale elements. This
means that we can interpret differences in the distance along the scale. We
contrast this to an ordinal scale where we can only talk about differences in
order, not differences in the degree of order.
Interval scale data would use
parametric statistical techniques:
Mean and standard deviation
Correlation - r
Regression
Analysis of variance
Factor analysis
Plus a whole range of advanced
multivariate and modelling techniques
.
Ratio
A ratio scale is the top level of
measurement and is not often available in social research.
The factor which clearly defines a
ratio scale is that it has a true zero point.
The simplest example of a ratio
scale is the measurement of length (disregarding any philosophical points about
defining how we can identify zero length).
.
Likert scales are a commonly used
way of measuring opinions and attitudes and apply to a range of disciplines.
They measure the extent to which participants agree or disagree with a given
statement, and typically range from 1 (strongly disagree) to 5 (strongly agree)
with a neutral point in the middle (e.g. neither agree nor disagree). They are
often analyzed under the assumption that they are interval in nature
Likert scaling is a bipolar
scaling method, measuring either positive or negative response to a statement.
Sometimes an even-point scale is used, where the middle option of "Neither
agree nor disagree" is not available
The format of a typical five-level
Likert item, for example, could be:
