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Methods for determining the uncertainty of population estimates derived from satellite imagery and limited survey data: a case study of Bo city, Sierra Leone.

Hillson R, Alejandre JD, Jacobsen KH, Ansumana R, Bockarie AS, Bangura U, Lamin JM, Malanoski AP, Stenger DA - PLoS ONE (2014)

Bottom Line: For five of those twenty sections, we quantized the rooftop areas of structures extracted from satellite images.Evaluations based either on rooftop area per person or on the mean number of occupants per residence both converged on the true population size.We demonstrate with this simulation that demographic surveys of a relatively small proportion of residences can provide a foundation for accurately estimating the total population in conjunction with aerial photographs.

View Article: PubMed Central - PubMed

Affiliation: Information Technology Division, Naval Research Laboratory, Washington, District of Columbia, United States of America.

ABSTRACT
This study demonstrates the use of bootstrap methods to estimate the total population of urban and periurban areas using satellite imagery and limited survey data. We conducted complete household surveys in 20 neighborhoods in the city of Bo, Sierra Leone, which collectively were home to 25,954 persons living in 1,979 residential structures. For five of those twenty sections, we quantized the rooftop areas of structures extracted from satellite images. We used bootstrap statistical methods to estimate the total population of the pooled sections, including the associated uncertainty intervals, as a function of sample size. Evaluations based either on rooftop area per person or on the mean number of occupants per residence both converged on the true population size. We demonstrate with this simulation that demographic surveys of a relatively small proportion of residences can provide a foundation for accurately estimating the total population in conjunction with aerial photographs.

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Related in: MedlinePlus

Residential and non-residential structures in Njai Town and Reservation.(A) Njai Town residence structures (blue) and non-residential structures (red), (B) Njai Town satellite imagery, (C) Reservation residential structures (blue) and non-residential structures (red), and (D) Reservation satellite imagery. When comparing either the maps or imagery for Njai Town and Reservation, note the differences in the map scales, which create the illusion that the structures in Reservation are smaller, although the average residential rooftop area in Reservation (255 ) is actually greater than that of Njai Town (172 ). The total land areas for Njai Town and Reservation are 0.21  and 2.33 , respectively. (Image copyright 2010 DigitalGlobe NextView License. Used with permission.)
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pone-0112241-g006: Residential and non-residential structures in Njai Town and Reservation.(A) Njai Town residence structures (blue) and non-residential structures (red), (B) Njai Town satellite imagery, (C) Reservation residential structures (blue) and non-residential structures (red), and (D) Reservation satellite imagery. When comparing either the maps or imagery for Njai Town and Reservation, note the differences in the map scales, which create the illusion that the structures in Reservation are smaller, although the average residential rooftop area in Reservation (255 ) is actually greater than that of Njai Town (172 ). The total land areas for Njai Town and Reservation are 0.21 and 2.33 , respectively. (Image copyright 2010 DigitalGlobe NextView License. Used with permission.)

Mentions: SIM04 and SIM05. Figure 6 shows the imagery and map of the Njai Town and Reservation sections. Residential structures are denoted in red; non-residential structures are denoted in blue. Figure 7 compares the rooftop-area population estimator under two different scenarios, both using DS03. In SIM04 only the 127 residential records are sampled – that is, all records drawn have 1 or more individuals as residents – but the total rooftop area is equal to the rooftop area of the combined residential and non-residential structures ( = 37,358 m2). This results in a total population estimate for Njai Town that is much greater than the true value. In SIM05, the population estimate draws on both residential and non-residential structures, so in some records the number of individuals is 0. This time the estimator converges correctly.


Methods for determining the uncertainty of population estimates derived from satellite imagery and limited survey data: a case study of Bo city, Sierra Leone.

Hillson R, Alejandre JD, Jacobsen KH, Ansumana R, Bockarie AS, Bangura U, Lamin JM, Malanoski AP, Stenger DA - PLoS ONE (2014)

Residential and non-residential structures in Njai Town and Reservation.(A) Njai Town residence structures (blue) and non-residential structures (red), (B) Njai Town satellite imagery, (C) Reservation residential structures (blue) and non-residential structures (red), and (D) Reservation satellite imagery. When comparing either the maps or imagery for Njai Town and Reservation, note the differences in the map scales, which create the illusion that the structures in Reservation are smaller, although the average residential rooftop area in Reservation (255 ) is actually greater than that of Njai Town (172 ). The total land areas for Njai Town and Reservation are 0.21  and 2.33 , respectively. (Image copyright 2010 DigitalGlobe NextView License. Used with permission.)
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4232376&req=5

pone-0112241-g006: Residential and non-residential structures in Njai Town and Reservation.(A) Njai Town residence structures (blue) and non-residential structures (red), (B) Njai Town satellite imagery, (C) Reservation residential structures (blue) and non-residential structures (red), and (D) Reservation satellite imagery. When comparing either the maps or imagery for Njai Town and Reservation, note the differences in the map scales, which create the illusion that the structures in Reservation are smaller, although the average residential rooftop area in Reservation (255 ) is actually greater than that of Njai Town (172 ). The total land areas for Njai Town and Reservation are 0.21 and 2.33 , respectively. (Image copyright 2010 DigitalGlobe NextView License. Used with permission.)
Mentions: SIM04 and SIM05. Figure 6 shows the imagery and map of the Njai Town and Reservation sections. Residential structures are denoted in red; non-residential structures are denoted in blue. Figure 7 compares the rooftop-area population estimator under two different scenarios, both using DS03. In SIM04 only the 127 residential records are sampled – that is, all records drawn have 1 or more individuals as residents – but the total rooftop area is equal to the rooftop area of the combined residential and non-residential structures ( = 37,358 m2). This results in a total population estimate for Njai Town that is much greater than the true value. In SIM05, the population estimate draws on both residential and non-residential structures, so in some records the number of individuals is 0. This time the estimator converges correctly.

Bottom Line: For five of those twenty sections, we quantized the rooftop areas of structures extracted from satellite images.Evaluations based either on rooftop area per person or on the mean number of occupants per residence both converged on the true population size.We demonstrate with this simulation that demographic surveys of a relatively small proportion of residences can provide a foundation for accurately estimating the total population in conjunction with aerial photographs.

View Article: PubMed Central - PubMed

Affiliation: Information Technology Division, Naval Research Laboratory, Washington, District of Columbia, United States of America.

ABSTRACT
This study demonstrates the use of bootstrap methods to estimate the total population of urban and periurban areas using satellite imagery and limited survey data. We conducted complete household surveys in 20 neighborhoods in the city of Bo, Sierra Leone, which collectively were home to 25,954 persons living in 1,979 residential structures. For five of those twenty sections, we quantized the rooftop areas of structures extracted from satellite images. We used bootstrap statistical methods to estimate the total population of the pooled sections, including the associated uncertainty intervals, as a function of sample size. Evaluations based either on rooftop area per person or on the mean number of occupants per residence both converged on the true population size. We demonstrate with this simulation that demographic surveys of a relatively small proportion of residences can provide a foundation for accurately estimating the total population in conjunction with aerial photographs.

Show MeSH
Related in: MedlinePlus