India, for example, has an average density of 324 persons per square kilometer, as per the latest census of 2001. Using the same notation, the sum of m trees model may therefore be expressed as: (10)Under the sum of trees model (Eq. These two analyses are hereafter referred to as being with or without population data, although neither uses current period population information to estimate population density. The predictive accuracy of river density may be understated in the Amazon basin because the river network is so dense that almost all land areas are accessible by river. This discrepancy in predictive accuracy demonstrates the potential of tree-based models for estimating population in data-limited areas. Compound measures are types of measure that involve two or more different units. Peru conducted a census in 2005, but the methodology and results were considered flawed resulting in the 2007 census When data are available, previous population metrics have obvious value for predicting current population. 2) Mortality- is the number of deaths in the population during a given period. In addition to measuring density, further information about a population can be obtained by looking at the distribution of the individuals throughout their range. For example, in order to determine the number of bacteria growing in a Petri dish . For lower weed densities increase the quadrant size (up to 1m 2) enabling counts between five and 50 plants per quadrant. Variable importance in the RF model was evaluated using two separate indices. As a result, population density is equal to the number of people that we divide by the land area. Human factors, including politics, lifestyle, and economics can affect population density. Population density can be used to describe the location, growth, and migration of many organisms. A GDP index derived from the 2007 and 1993 censuses was downloaded from the INEI as an economic indicator for the analysis. order to reduce the proportions down to one measure of diversity, I use Shannon's diversity index [7]: diversity = X6 i=1 p i lnp i: This resulted in diversity scores ranging from 0.4 to 1.6. As satellite-based thematic land use classification in humid tropical regions is still a topic of active research [36][40], we choose to use NDVI and LST instead of relying on an error-prone land use dataset. The predictive accuracy of each model, both with and without population information, was evaluated using 300 repetitions of a random 10% holdout analysis. Population density refers to the number of individuals per square kilometer of land area. 2. However, they are well-understood and physically meaningful variables that are indicative of differing land cover patterns and physiographic conditions that are likely to be relevant to the distribution of population. Population density ranged from 10 persons per square mile in Liberty County to 3,348 persons per square mile in Pinellas County. Crude or arithmetic density can be worked out separately for rural and urban areas. The measurement is normally illustrated as the number of people per square kilometer or square mile. Wrote the paper: WA SG BZ WP. Estimates of the distribution and growth of human population are invaluable. A Tool for Measuring Population Density A Tool for Measuring Population Density 1972-10-01 00:00:00 a device for measuring the density of living units per acre is presented in Density: Five Perspectives (Washington, D . We emphasize that the analysis is not a complete assessment of SAE methods, but is specifically focused on methods of producing estimates when no direct estimates are available for a particular administrative unit of interest. The population density of the planet (including all land area) is about 38 people per square mile (57 per sq km). But it is also true that not all the people in a region or country are dependent on agriculture. Agricultural density is, thus, the ratio between the number of people earning their living or subsistence from working the land and the total amount of farmland. Step 1 -The outlines of the sites to be measured were created by performing an Just as in the case of density, geographers use a number of measures in the analysis of population distribution in any country or region. This is likely another indicator that, as previously discussed, the data is highly nonlinear and may not be well represented in some of the area-level covariates due to heterogeneity within individual districts. Though, there are several measures used by geographers, the ones relating to the centrality, dispersion and concentration of population are very important. Model errors and p-values assessed using population count error as a proportion of actual district population: |PredictedActual|/Actual. province noun division of a country larger than a town or county. Microsimulation produces SAE population estimates by modeling specific individuals or households and, in the case of dynamic microsimulation, life events of those individuals [3][4]. 2. Measuring Population Density density within the outlines. density within the outlines. 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 . Population density is the average number of people living in a given area. For this study a consistent month during the dry season was chosen (July). In the modified equation the distance between each settlement and the mean centre is multiplied by its population and then aggregated. 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. In biology, a population is a group of organisms of the same species that live in the same area. This can be concluded from the measurements of monitoring networks, where we observed higher E-field values in those countries where the sensors are located in places with higher population density. Changes in the amplitude of vibration can be measured when the object is struck periodically, like a bell. Statistical modeling in the context of SAE refers to model-based methods of producing estimates, often described as synthetic estimates, which may be used directly or blended with design-based measurements to produce a final estimate [1][2]. Agricultural density - total number of farmers per unit of arable land. Following the notation of Chipman et al. for a given T and M, g(x; T, M) denotes the function that assigns i M to x. broad scope, and wide readership a perfect fit for your research every time. Such a person might opt to live in the suburbs of a big city, where they would have access to slightly more living space, but still have access to the kind of amenities a big city has to offer. It includes natality, mortality, emigration and immigration. The map below is a choropleth (shading) map and illustrates population density. Notably, when population information was not included the RF model was the only model to significantly outperform the no-model alternative as assessed by population density. The total population count of all five regions increased from 1993 to 2007 (see Table 2) with a slight skew towards growth in more populous districts (see Figure 1), which broadly reflects the overall population dynamics of the country as a whole [16]. Model errors and p-values assessed using population count error as a proportion of actual district population: |Predicted Actual|/Actual. Random Forest the model that provided the best population density estimates for the analysis - indicated that the majority of remaining covariates had comparable variable importance (Table 8). For this study, remote sensing data collected by the MODIS Terra sensor was included directly as an indicator of land surface conditions. The suite of models is assessed using average mean absolute error (AMAE) as a measure of general model accuracy as well as average root mean square error (ARMSE). ; Complete assignment and submit by Blackboard. Population density is the measure of the number per unit area. The Population Density Calculator can give you the results very quickly by following these steps: 1. Module 5 - Measuring Plant Density < Return to Schedule: Lesson Instructions. The main advantage of the median centre is the fact that it can easily be worked out without resorting to too much of mathematical calculations. See answer (1) Best Answer. In contrast to the regression models, the RF model a non-parametric tree-based model - provided among the most skilled estimates when 1993 population density was not included in the covariates, but among the least skilled estimates when it was (see Tables 3 through 6). It's usually more. Give your answer to 2 decimal places. 1 Includes the resident population of the 50 states and the District of Columbia, as ascertained by the Decennial Census.. It is often these same data-limited regions that lack information from previous time periods for use in training and testing models. London, Paris and Buenos Aires are striking examples of uni-modal centres in the United Kingdom, France and Argentina respectively. Nicholas School of Environment and Duke Global Health Institute, Duke University, Durham, North Carolina, United States of America. It is a common biological measurement and is more often used by conservationists as a measure than population size. Content Summary Assignment due by Midnight on . As already stated, population geographers have long been concerned with the uneven distribution of population over the earth surface both at a given point of time and as an evolutionary process. When a scientist counts a species' population in a discrete portion of a habitat, the density figure can be applied to the entire habitat to get a reasonable estimate of the total population. They proposed the population diversity index, a measure conform to the human perception of how diverse a set is, based on the Shannon entropy [206]. Our analysis includes versions of both linear models and linear mixed models as established linear modeling structures against which the performance of nonlinear methods may be evaluated. Of the various measures of central tendency in a spatial distribution, the mean centre is the most useful tool for studying the aerial shifts in population distribution over time. The way human beings govern themselves can have a profound influence on population density. The overestimation bias for lower-density districts is not surprising given the relatively small margin available for underestimation in such districts. Furthermore, the vast majority of Canadas population lives in the south of the country close to the border with the U.S. (iv)Population density can be given by the following equation N t+1 =N t + [ (B + I) - (D + E)] this is density at time t+ 1. where, N = Population density, t = Time B = Birth rate, I = Immigration, D = Death rate, E = Emigration and N t = Population in beginning. Ecologists estimate the size and density of populations using quadrats and the mark-recapture method. The GHSL population layer shown in the map describes residents per square km, related to the underlying census data . Model errors and p-values assessed using density, population data included in the covariates. The analysis is relevant for regions with limited reliable census data. One type is physical factors and the other type is human factors. People are more likely to live where the climate is suitable for cultivation. The RF model structure is similar to a bagged CART method, except that a random subset of variables less than the total number of variables are chosen to use at the splitting point for each tree. Concentration of population in an area is maximum in a hypothetical situation where the entire population is concentrated at one point and minimum where the individuals are located at an equal distance from one another. This is done by assigning some weight (i.e., population size in the present case) to the x and y axes for each point and then working out the weighted mean. One approach to reduce the variability inherent in predictions from CART models is to use model averaging based on bootstrapping, a method known as bagging [22]. Step 3 -The Population Density command is called. The prior is designed to regularize individual tree influence such that the effect from no one tree dominates the model. You can use square feet or meters if you are finding the density of a smallish space. Observations of district population density (black points) are ordered from lowest to highest density. 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). This serves as a point of caution when interpreting any single prediction from a model optimized for predictive skill across a large and diverse study region. Two distinct components make up SAE: design-based methods and model-based methods, which may be further divided into area-level models and unit-level models that employ either frequentist or Bayesian frameworks [1][2]. Funding: This research was supported in part by NASA Applied Sciences award NNX11AH53G. Regions are the basic units of geography. Population density allows for broad comparison of settlement intensity across geographic areas. This may occur due to reproduction, hatching or germination. The crossword clue Unit in measuring population density with 10 letters was last seen on the January 01, 2010. It is commonly represented as . (2) Percent cover or biomass is also used to measure the population . In the calculation of comparative density, total population of a region is related to the aggregate of weighted land according to its productivity under cultivation. For instance, The population density of the Los Angeles Metroplex . The LM model structure provides a point of comparison with the LMM to determine the marginal benefit of adding spatial correlation, and provides perspective on the performance of each of the more complex models. Census population density vs. Random Forest estimated density. After standardizing the data, out of 417 districts present in each year (according to the most recent INEI report) 412 districts mapped to those in the Digital Chart of the World. The population dynamics in these districts are likely controlled by variables not captured in our analysis or exhibit an anomalous relationship between the covariates and response variable. doi:10.1371/journal.pone.0100037, Editor: Hiroshi Nishiura, The University of Tokyo, Japan, Received: July 20, 2013; Accepted: May 21, 2014; Published: July 3, 2014. Eight districts were created due to redistricting between 1993 and 2007, seven of which resulted from splitting an existing administrative area into two separate districts. Second, we calculate the land-to-density indicator for . We think the likely answer to this clue is SQUAREMILE. 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. Sporadic population data collection such as the gap between the 1993 and 2007 census in Peru is common in low- and middle-income countries. Since the location of median centre is not fixed, its use should be restricted to preliminary investigation only (Ebdon, 1985: 133). The 63-page, illustrated book reports results of the institute's third annual land use symposium. 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).
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