Population Potential: Step by Step Calculation

Introduction:  

The concept of Population Potential (Demographic potential) was propounded by Stewartz and Warntz (1958) to analyze the accessibility of a point to the population of the region. The model is directly derived from gravity model in a simplified way.

• It is a measure of the spatially distributed population with respect to a point. 

• It indicates the intensity of possible interactions between social or economic groups at different locations (Mfungahema & Kitamura, 1997). 

• Population Potential is a measure of nearness or accessibility of a given mass of population to a point. 

• Population potential encompasses the influence of all other points on a particular one. 

• It is an index of mass or gravity of points with respect to its population in relation to distances to all other points. 

The term is derived from social physics and the concept is closely related to the Gravity model although in total, population potential relates mass population to distance whereas the gravity model deals with a separate relationship between pairs of points. 

The population of different areas as a measure of their masses may be replaced by some other suitable mass in different situations. 

For example, if inter-metropolitan migration is to be studied, it is apparent that employment or income of the areas tends to be more significant than the population. Here simply per capita income can be multiplied with the population and taken as mass  (Mahmood, 2013). 

When the problem of marketing of manufactured products is being examined, the total value of retail and wholesale tends to be more important than population (Mahmood, 2013). 

Thus the measure of mass to be used based on the nature of study availability of data and related other consideration (Isard, 1960).

The distance between the two areas can also be measured in different ways. If a metropolitan traffic study is to be conducted, distance along the road or Highway or travel time is equally important.

If industrial location is being analysed transport cost distance is preferred instead of simple distance.

Objectives:

• To find out the interrelationship among the centers. 

• To show the accessibility among the centers. 

• To find out the influence of any major concentration in terms of the probability of migration and spread of concentration. 

• To find out the probability of attracting the population of all other points to a particular points.

Formula for Calculation:

 

Steps of Calculation:

• Prepare a square matrix for all the population centres.

• Measure the distances between points from the given map anong transport routes and note down in the distance matrix (To determine the distance between same points in the matrix (in the main diagonal) consider half of the distance of its nearest point.)

• Prepare another square matrix (population potential matrix) and note down the population potential values in each cell. 

• Complete all the cells.

• Make row sum. The population potential of each point is its column sum.

• Plot the population potentials on the map and draw iso-lines and mark zones (Higher the value, higher the population potential and thus higher concentration of symbols/ colour).

Example: 

 

Exercise: