It is no wonder, then, that a large part of Indias population lives in the area that surrounds the Ganges River. There is arithmetic density, physiological density, and agricultural density. Population density obtained from the 1993 census was incorporated as a measure of population in a previous time period. Human factors include political circumstances, such as the stability of the government in a certain area; lifestyle factors, such as whether people want to live close to each other, and economic factors, such as the location of jobs. Measures of Density: Crude density, also known as arithmetic density, is the most commonly used measure of population density. Step 3 -The Population Density command is called. region noun any area on Earth with one or more common characteristics. The fundamental act of choosing a model structure will significantly affect the population estimate and the understanding of covariate influence. Daytime LST may act to differentiate between the diverse land cover of Peru, which includes open water, bare soil, forested areas, rock and urban areas. Step 3 -The Population Density command is called. NDVI was available as a 1 km resolution gridded product, but was aggregated to district averages using the administrative boundaries to match the resolution of the other covariates. Indeed, some of the worlds most densely populated countries and territories are those that are very small in area. This makes them particularly accessible tools for providing robust model estimates. In this analysis, six regression and tree-based models were chosen to explore how predictive accuracy and variable importance changes in the presence or absence of population information. Evidences indicate that most of the countries of the world with one principal peak of population potential are uni-modal. Seth Guikema, Examples of the causes in low population densities include: A) Classified land cover. It is often these same data-limited regions that lack information from previous time periods for use in training and testing models. In contrast, a person who prefers to have a lot of space and not be too close to other people might seek to live in a rural area, perhaps in a small town. Thus, physiological density also does not provide an accurate picture of population pressure on land. This paper explores the extent to which the availability of data from previous time periods affects the choice of optimal model structure for area-level SAE models. The analysis may be broadly categorized into two sections: one in which population density from 1993 is included as a covariate and one in which it is excluded, leaving only socioeconomic and environmental covariates to predict population density in 2007. Affected districts were recombined to pre-2007 boundaries, and all relevant variables were re-calculated. But of course, water isnt the only resource coveted by people looking for places to live. In addition to being used to disaggregate population densities, remote sensing is perhaps even more valuable for statistical population models in which it is used to estimate population density. No additional specifications were required for the RF, MARS or BART models. Isolated districts across the domain display large model errors, which demonstrates the limitations of using model-based population estimates alone. Some countries are bi-modal with two peaks of potential, for example, Sydney and Melbourne in Australia. The most common way that this is done is to relate the remotely sensed data to land use and to include that information in a regression-based model that is identified and trained using one dataset and evaluated using a separate dataset from a culturally and demographically similar area [30], [34]. The scale of our study precluded the use of direct estimates of density such as counting dwellings, but measures of the land surface conditions were incorporated in the form of NDVI and daytime LST, as described in detail below. Pythagoras' theorem - Intermediate & Higher tier - WJEC, Trigonometry Intermediate & Higher tier - WJEC, Enlargements/Similar shapes - Intermediate & Higher tier - WJEC, Conversion between metric and imperial units - WJEC, Dimensional analysis - Intermediate & Higher tier - WJEC, Home Economics: Food and Nutrition (CCEA). Stated rather simply, population density is a measurement of the number of people in an area relative to its size. The final equations corresponding to the two axes of the mean centre are thus: Where, xi and yi are the co-ordinates of the ith town or village, p is the population of that town or village and P is the total population of the region. This procedure involves three steps: Step 1 -The outlines of the regions to be measured are created and saved to a file. Though, there are several measures used by geographers, the ones relating to the centrality, dispersion and concentration of population are very important. Arithmetic density - the number of people per unit of area (i.e., the same as population density). Figure 5 demonstrates that the RF mean is significantly skewed towards the high end of the QRF distribution, at times falling outside of the 95th percentile. It is specifically applicable to human beings and is an important expression. In relation to the equator it is seen that the vast majority of the human population lives in the Northern Hemisphere, as 67% of Earth's land area is there. The measure of variable importance used for a GAM was the increase in average MSE that results from removing a specific variable. 2 is also the Bayesian predictor under normality of the error terms when using a diffuse prior for . Similarly, a point can be located in the distribution from which the sum of distances to all the points is a minimum. Igcse & a-level geography: population density and distribution *igcse*. Remotely sensed data derived from aircraft or satellite has a fairly long tradition in population modeling. Department of Earth and Planetary Sciences, The Johns Hopkins University, Baltimore, Maryland, United States of America, Affiliation: Population density is calculated by dividing the number of people by the area. The tendency of a population distribution in any region towards either of the two hypothetical extremes can be measured by means of a graphical device known as Lorenz curve. The Himalayas are home to some of the worlds tallest mountains, including Mount Everest. Copyright: 2014 Anderson et al. In our analysis we propose a number of model structures that provide accessible alternatives to more complicated methods, which often require precise user specification to produce accurate estimates. A variation of the penalized splines method is included in this study, as discussed further in the following section. While microsimulation and areal interpolation are valid approaches to SAE problems, this paper focuses on an assortment of statistical modeling methods. Variable influence in the MARS model was based on the contribution of a variable towards reducing the models generalized cross-validation (GCV) score. Multiply densityb y total size of area for total population size. Arithmetic density: The total number of people / area of land (measured in km2 or sq miles). GCV is an approximation of the leave-one-out cross-validation using a squared error loss measure [22]. For the purpose of population estimation in this study, errors between districts are modeled using exponential spatial autocorrelation according to the centroid of each district. The most basic tree-based structure is the Classification and Regression Tree (CART), which recursively partitions the data into i subspaces and applies a very simple model to each subspace. The best linear unbiased predictor (BLUP), , under this model is defined as(2)where i is a tuning coefficient defined using the variances of ui and as . Put simply, population density is the measurement of the average number of people in a given area. It is the first to measure the population-to-density indicator with such a wide spatiotemporal resolution, i.e. Each subzone is assigned a population density such that the sum of population over all subzones equals the population of the original source zone [6]. ui and are mutually independent error terms where ui represents the random effects of area characteristics not accounted for in the covariates. People also want to live in areas where there is good soil for farming, good pastureland for grazing, abundant fishing stocks, and raw materials for building structures and fueling industry, such as wood, oil, and coal. The prior on T puts a larger weight on small trees and the prior on shrinks the fit of each terminal node proportional to the number of trees such that the contribution of any one tree decreases as number of trees increases. It is commonly used to compare how 'built-up' two areas are. Those larger in size will, therefore, have a greater influence on the location of mean centre. [25]. Tree-based methods are often most useful for models that are highly non-linear. This is called the Allee effect, after W. C. Allee who first identified it. This is done by calculating the co-ordinates of each point according to an arbitrary system. In groups of 2-3, use the population statistics packets and the maps on my teacher page and on the board to formulate at least two new hypotheses regarding the possible correlation between a measure of density and another population statistic. In addition to the physical characteristics of the study region, we used an index of GDP as an economic indicator for each region. These models are often used, for example, in problems of disease mapping [9]. Nicholas School of Environment and Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America. The calculation of standard distance for points corresponding to settlements of varying size of population requires modification in the equation accordingly. Despite this potential, the application of SAE methods in resource-poor areas is somewhat limited. Despite the fact that the regression based models (LM, LMM, GAM and MARS) provided the most skilled predictions of population density when 1993 population density was included in the covariates, these models- with the exception of the LMM- provided among the worst predictions when no population information was included (see Tables 3 and 5). It is calculated by dividing the number of people in a certain area by the size of that area. Population density (often abbreviated PD) is a compound measure that tells us roughly how many people live in an area of known size. In this study, we have extended the idea of incorporating information on transportation corridors to include navigable bodies of water. Proximity to transportation corridorsboth roads and navigable riversmay be especially important in the Amazon where large tracts of forest make transportation difficult. Sign in, choose your GCSE subjects and see content that's tailored for you. B) Regions included in the analysis (Apurimac, Arequipa, Ayacucho, Cusco and Madre de Dios). This video is an elaboration of the process in Population Density and Biodiversity: Knowledge Catalog Grade 9 Biology #12. The population density of the planet (including all land area) is about 38 people per square mile (57 per sq km). If 2 is taken to be the variance of an individual tree, and is the correlation between tree predictions, then the variance may be represented as(8). Thus, Population Density = Number of People/Land Area. The no-model mean estimate was simply calculated as the mean of available response data in the holdout dataset. Even when compared to the average model in which population information is available, the RF model produces errors that are only two to four times greater and therefore still useful in an applications context. Population density is an often reported and commonly compared statistic for places around the world. Examples of compound measures include m/s, g/cm, population per km and miles per gallon. Population density is the measure of the population number per unit area, according to About.com. Small area estimation (SAE) refers to methods for estimating small-scale characteristics of populations when there is little data, or in some cases no data at all. In the same respect, areas where the climate is too hot and too dry for cultivation are also sparsely populated, which is why you wont find too many people living in Africas Sahara Desert. Crude or arithmetic density can be worked out separately for rural and urban areas. Communities are made up of populations of different species. The location of the centre of minimum travel can be determined by the process of trial and error, i.e., by measuring the aggregate travel distances pertaining to several probable points and then selecting the one which gives the lowest value.