Nigeria Population Map Metadata Report

The weighting layer here below represents the estimated population density in each 3 arc seconds (approximately 100 m at the equator) obtained using the Random Forest (RF)-based dasymetric mapping approach developed by Stevens et al. (2015)*. This weighting layer is then used to dasymetrically disaggregate population counts from administrative units into grid cells to obtain the final population distribution datasets (both remaining unadjusted and being adjusted to match the most recent UNPD estimates# available at the time of production). A brief description of the RF model and all its inputs, including the source and spatial distribution of each covariate, is also provided in this metadata report.

*Stevens, F. R., Gaughan, A. E., Linard, C. & Tatem, A. J. Disaggregating Census Data for Population Mapping Using Random Forests with Remotely-Sensed and Ancillary Data. PLoS ONE 10, e0107042 (2015).
https://esa.un.org/unpd/wpp/Download/Standard/Population/ 




Call:
 randomForest(x = x_data, y = y_data, ntree = popfit$ntree, mtry = popfit$mtry,      nodesize = length(y_data)/1000, importance = TRUE, proximity = rfg.proximity,      do.trace = F) 
               Type of random forest: regression
                     Number of trees: 500
No. of variables tried at each split: 8

          Mean of squared residuals: 0.275253
                    % Var explained: 85.27

Random Forest Diagnostics

Covariate importance for NGA RF Model Prediction Error (MSE) Stability for NGA RF Model

Covariate Metadata

Distance to cultivated areas 2006 Distance to woody areas 2006 Distance to cultivated areas 2006 Distance to herbaceous areas 2006 Distance to sparse vegetation areas 2006 Distance to aquatic vegetation areas 2006 Distance to Urban area 2006 Distance to bare areas 2006 Distance to inland waterbodies 2000s Distance to Urban area 2006 Distance to settlement buildup areas 2000 Distance to major road intersetcions multiple years Distance to major waterways multiple years Distance to major roads multiple years Current average total annula precipitation Current average annual temperature Slope Elevation Distance to coastline Distance to CAT1 protected areas 2006 Nighttime lights 2006 DMSP