There have been assorted theories presented to explicate how the distribution of metropolis sizes can be done in both regional and urban analysis. It is nevertheless agreed that this affair is really of import to all communities. It can be referred to as a planetary concern because it affects everyone. Assorted theories have been frontward to do sense of this challenging phenomenon.

Hierarchy theoretical accounts have had much certification since the initiation of the cardinal topographic point theoretical account. This theoretical account produced deductive consequences that could be used by statisticians and other societal scientists.Accredation to this theory is given to Beckmann who based his theory on a set of premises. This made apprehension and reading easier. His theoretical account related the metropolis country, market place, scope and threshold into one. The size of the metropolis country is served by a market topographic point tantamount to its size. The threshold and scope are the economic systems of graduated table and the conveyance costs are the bounds in the metropolis countries. The hierarchy starts from the little metropoliss functioning the rural countries and ends with the big metropoliss that serve the big urban population.This theory is acceptable if Beckmann ‘s premise that all metropoliss of the same rank are of equal size. The alterations have taken into history non-place maps such as spacial differences in the impact of engineering make this theory feasible for use in giving an account to the distribution of metropolis sizes. Oppositions of the cardinal theoretical account theory insist that the simple premises make it unrealistic. Without judging the basic theoretical account, defenses have been made with regard to the rural population upon which the distribution of the metropolis size is generated. This is an ambiguity because the metropolis and rural countries are accommodated in an issue biased to cities.Furthermore, this theory does non do realistic allowances for high conveyance costs, denseness factors ( e.g. congestion ) and other anomalousnesss that are likely to happen in a metropolis ( e.g. environmental pollution ) .for intents of understanding the distribution of metropolis sizes, the cardinal topographic point theory acts as a good starting point because it defines an ideal state of affairs.

The 1967 Tinbergen urban hierarchy theoretical account takes into history the income of the metropoliss being described and assumes the highest order good are exported.It is suited for the fabrication industry. An economic system of a geometric signifier with evenly spread farms except in the metropoliss is the chief givens made for this theory to be effectual. The advantages of this theoretical account are that it can be used to prove generated hypotheses and it can be modified by doing an adjustment for complexnesss ( e.g. foreign trade, complex interurban trade flow or intermediate merchandises ) . Supporters of it are those who have generated projections from it in the fabrication sector. Those who do non hold with the theory are most likely those who do non hold an involvement in the fabrication industry.

The administrative hierarchy theoretical accounts is one that has been used in socialist economic systems due to the extremely administrative nature of socialist states that have low promotion in service maps. Since this is a particular hierarchy catering to the construction of socialism, defenses are seldom made. In fact, versions of this system integrated metropoliss that have a strong administrative hierarchy. The challenge confronting this theoretical account is the control of the mean figure of controlled centres which are the parametric quantities used in implementing this theoretical account.

Stochastic theoretical accounts are besides used to work out the challenge of distribution of metropolis sizes. The chief determiners of urban growing are taken to be relative to metropolis size. Get downing with the jurisprudence of proportionate consequence, the deduction made is that the growing of the metropolis is straight relative to the size of the metropolis. It gives infinite to demographic factors ( e.g. migration and emerging metropoliss traversing the minimal threshold ) and non demographic factors if their influence on the size of the metropolis is proportionate to the size of the metropolis. Its major drawback is its random nature with no trust on systematic factors. This theory has few protagonists due to its indiscriminate nature and unrealistic application on the existent growing rate in the distribution of metropolis sizes.

The theoretical account of market chances was created utilizing the rules of the jurisprudence of proportionate consequence but its chief accent was migration.Moreover, employment chances straight affect the migration procedure and are straight relative to the the metropolis sizes. This theory is applicable in parts that have resources that can back up their population. It is disapproved because it is extremely dependent on the civilization of market oriented economic systems. It is non realistic because in today ‘s present culure, rural-urban migration is high and there is a lack in the rural countries doing an instability in the available resources in an country.

The information maximization stochastic theoretical account measures the grade of equalisation reached within a system and when this is maximized, equilibrium is achieved. Positive responses to this theory suggest that it is the most realistic of the full stochastic theoretical account because it achieves the most plausible distribution of an arbitraryarrangement of a known population in a given figure of metropoliss. Its negation is the unsystematic forces used in its premises.

Stochastic theoretical accounts are really utile if the premises made in each theoretical account are functional to the appropriate instance. They have a haphazard mode in their formation. They can be used more intentionally in many more instances than the hierarchy theoretical accounts if restructuring and more order is introduced in the constituted theories.

Quasi-economic theoretical accounts use theories developed from economic sciences tax write-offs. The growing theory theoretical account integrates growing theory with a random procedure to come up with a lognormal distribution of metropolis sizes. The growing refers to the measure of metropolis labour forces and this can is expressed as a map of efficiency advancement of the labour. The strength of this theory lies in its illative economic hypothesis to assume a lognormal distribution of metropolis sizes that is consistent with experiential observation. Expostulations to the premise that nest eggs and investings are equal in the population and that a metropolis has a absolutely elastic labour supply would be the greatest failing of this theory. Provided a balance of labour forces and equilibrium in market merchandises exists between the metropoliss in this theoretical account, it is acceptable to utilize it in determning the distribution of metropolis sizes.

The following quasieconomic theoretical account is the neoclassical equilibrium theoretical account which makes premises of fringy productiveness between metropoliss and that migration occurs as the population seeks higher income. The mathematical life scientist who formed it ( i.e.Rashevsky in 1943 ) expressed the productiveness of the urban population as a map of the metropolis size and population features of the whole system. This theory is non acceptable because it is non matter-of-fact with the distribution of metropolis sizes in the existent universe. Hence accommodations need to be made.Firstly, the maps of the urban population should be taken as log usually distributed.Secondly, the industries among metropoliss must be distributed hierarchically within a model of multiple sectors. When these are incorporated to this theoretical account, it can so be used.

The 1949 Zipf theoretical account is acknowledged for its empirical rank-size relationships in the economic systems of scale -transport costs. However his theoretical attack is non satisfactory because his general analysis utilizing societal organisations regulating forces has direct analogies in economic science. This in bend makes his constructs equivocal in nature and hard to utilize. It does non sufficiently specify the Pareto distribution which is the underlying construct of the practical theoretical accounts used in distribution of metropolis sizes. His first manus information has proved more utile than the theory that has made a failed effort harmonizing to critics such as Isard in 1956.using his theoretical account would be litigious but with careful defense mechanism, it is possible.

The 1972 Evans thought of nines or alliances makes much sense when applied to concern organisations that have a hierarchy of metropolis sizes. Its flexibleness with regard to fluctuation of input costs and market chances, and, the family theoretical account alteration make it believable in guess. The chief consequence that the size of a metropolis decreases with addition in the figure of metropoliss makes the calculation of Evans suggestion suitable.

The allometric growing jurisprudence derived from animate being biological science has been put up as an account to metropolis size distribution. Beckmann tried to give a relationship between this jurisprudence and the Pareto distribution but it was non successful because critical statistical maps are similar. This is non valid to doing right illations on metropolis size distributions. He subsequently made an effort to demo a theoretical nexus between the two relationships. His given was equal for some until the theoretical account of growing diffusion was introduced.Consequently, his premises can be used if an person wants to do ideal deductions of metropolis size distribution utilizing similar statistical maps and theory. The general systems theory arose as the allometric growing theory was being analysed.In 1964, Berry was unsuccessful because he did non foreground the realistic application of this theory in work outing the issue. In 1969, Wilson made it clear that several systems are involved in unknoting the distribution of metropolis sizes. This meant the general systems hypothesis was undependable of all time since.

The new theoretical accounts such as the Markov Chain theoretical account and the Central Limit Theorem give more possibilities to the theoretical work suggested or established before. An unconstrained Markov theoretical account introduces an component of order that allows different passages to hold different chances. This already brings order to the maximal information theory mentioned before. This means that a Markovian Chain theoretical account can be used to bring forth several alternate metropolis size distributions. Provided accommodations are made to these Chain theoretical accounts, they can expeditiously be used to do metropolis size distribution illations.

The Central Limit theorem is a statistical attack that enables a similar analysis to be applied to legion independent factors combined multiplicatively at any given minute. The advantage of this theorem is that it is really realistic in the universe to explicate the metropolis size distribution. This theoretical account is one that should be used more than others because it accommodates the complexnesss that influence the distribution of metropolis sizes. Its lone downside is that it gives consequences for a given point in clip without taking into account historical or future events that can impact metropoliss. However this should non be catastrophic because possible variables reflect factors that are built over clip. Since size distribution of metropoliss is stable over clip, it is really likely that the distribution of determiners act uponing metropolis size distribution is besides stable.

In decision, I would state that the topic of metropolis size distribution can be solved by taking each instance survey consequently. This means an in-depth survey of each instance should be done and assorted theoretical accounts tested to do observations and sensible decisions. The theoretical accounts with more pros than cons for each circumstance presented should do as executable methods of geting replies to this combative issue.