US population change in 2001-2002
The data was obtained from the U.S. Census Bureau website. It consists of 2000 population census, birth and death rate for 2001, international and domestic migrations also for 2001. The data is categorized according to states.
The data was analyzed in order to determine the relationship between the population census and other parameters outlined above. Fig. 1 shows the distribution of the US population across the 50 states. The results indicate that the state of California has the highest population, followed by Texas and New York states in that order. The state of Wyoming has the smallest population.
Fig.1 population distribution in the US -2000
The data was further analyzed to determine the relationship between the population size and the area of the state.
The following hypotheses were put forward;
Population size and the area of the state
H0: the bigger the size of a state area the higher the population size
H1: there is no relationship between the size of the state and the population size.
Birth rate and death rate
H0: the areas with high birth rate have high death rate
H1: there is no relationship between birth and death
rate
International and domestic migration
H0: areas with high international migration have high domestic migration rate
H1: there is no relationship between the domestic and international migration rate
Results:
Using the two-sampled t-test the results indicated
that there was no relationship population size and the size of the state. The data was further sorted and summarized by the regions. Still there was no correlation between the size of the region and the population size of the respective region, as indicated in Fig 2 below.
Fig. 2 The distribution of US population by regions
Two-samples t-test was also performed on the rate of birth and death per state. The results showed that there was no correlation between the two. The graphical representation of the results in shown in Fig 3.
The correlation between the international and domestic migration per state was tested using the two-sampled t-test. There was no correlation between the two. The results are show in the scatter plot below, Fig. 4.
Fig. 4 The relationship between the rate of domestic and international migration
Discussion
The results show that all of the observed parameters occur independent of each other. For example, the big states (in terms of size) with do not necessarily have high population or birth rate. The reason why there is no correlation between the size of the state and its population could be attributed to the type of the landscape. Some areas maybe not suitable for human land use, for example, the desert. In this case a large portion of land will remain unoccupied. The shortage of suitable land might the lead to shortage of resources and as a result depresses the population growth.
Birth rate per state did not have correlation with death rate. It is difficult to explain the lack of correlation between these two variables.
The other variables that were examined were the international and domestic migrations per state. The results showed no relationship between the two. Also there was no relationship between the population size and the migration type.
Data source: http://www.census.gov/popest/national/files/NST_EST2009_ALLDATA.csv
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