An important topic of regional analysis.

The word DISPARITY implies lack of equality between people or things; dissimilarity.

Indicators of development, occuring in the region of study,  should be used. All / most developmental indicators have different units, so they should 1st be brought on an equal level / unit for measurement.

Disparity can then be measured by using the following popular methods:

i) Composite Index;  ii) Range;  iii) Coefficient of Variation;  iv) Gini Coefficient;  

v) Theil's T Statistic;           vi) Range Ratio. 

I have used first four methods individually and in combination, for calculating spatio-temporal dissimilarity; the results thus obtained are near to reality.

After calculation, the results must be mapped cartographically, ie., a chorochromatic map should be plotted. The map drawn gives an idea about the actual location patterns of dissimilarities within micro, meso and or macro areal units.

Hope this information satisfies you.     

You may see this paper

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Subir

Article An Evaluation of National Highway Network Expansion Policy i...

You may see this paper also.

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Complimentary to measuring the disparities it may also be useful to identify how they evolve with time. We speak then on convergence or divergence. For doing so one useful method is to use sigma and beta convergence indicators. 

For an example where such indicators are applied you may look at the following article: 

Hope this is useful

Article Disparidades e Convergência Interregional no Alentejo

Many thanks to Ricardo!. It is very useful one.