Thurston scaling is the most important type of one-dimensional method. Thurston developed three different approaches of scaling which are most probably different in measurements and scaling as well. These are;

•    Equal appearing intervals method
•    Successive intervals.
•    Paired comparison method.

The Method of Equal-Appearing Intervals

Developing focus:

The method of equal appearing intervals begins with the strong focus on the statements.  First to focus on the formulation of the scale that is going to be used. As the concept is one dimensional so the project preferred should be of single dimension. The explanation of the project should be very much clear so that one can know about the measurement levels. The statement developed for the scaling is formulated in a way that every respondent should have the idea of such statement. 

Generating potential scale items:

After attaining the focus, statements are built which may be in the range of 80 to 100. While the formulation of statements it is very obvious that the grammar and sense of all the statements be same. So that very minimum difficulties be faced while assigning the scale to such statements.

Rating the scale items:

Objects are rated in three possible factors like enormously favorable, enormously unfavorable and neutral (neither favorable nor unfavorable). In the scale only end points are mentioned that are favorable and unfavorable and the middle point that is neutral. The rating done on statements are the representations to know the extent of individuals. For example; if the question is distributed to fill it up that may be;

•    Are you satisfied with the performance of your boss?

In response to the above questions, the three possible answers might be given from different respondents which are then plotted on a scale.

Evaluation of scale scores:

After the ratings on different statements, the computation is made through Median and Quartiles Range and classification is made in between the different quartiles in order to provide numbers. And the lowest valued quartile is positioned; such attempt provides the actual rating of the collected data.

Successive Intervals

Paired Comparison

In paired comparison method, the judges are more focused in the selection of each possible pair within the potential statements. The paired comparison method is only valid when the statements are limited because the increase in comparison, squares each statement.

Comparison between the Methods

All three methods of Thurston scaling are comparatively similar but the difference occurs in the collection of data by the judges who examines the data. In the Thurston scaling there come a problem in all three methods that are the judges because it is very difficult to gather the judges who have a broaden vision to understand the accessed data.

References

•    www.changingminds.com, accessed on April 10, 2012.
•    T. William, (2006) Thurston scaling.