The referral analysis allows one to compute the travelling times and/or the distances along the least-cost paths (i.e. path between two locations that minimizes the total travel duration for those travelling along it, see Ray and Ebener, 2008) between two groups of health centers. Such path is different from a straight line as it does take into account the landscape constraints together with the modes and speeds of travel of the population.
...
(3) Under “Type of Analysis”, select the option to do an anisotropic analysis as you did for the previous analysis
(4) The option to use "knight's move" allows one to perform an analysis on 16 neighbors cells instead of 8. It is slower, but more accurate and tends to give more rounded catchments in area of uniform landcover. We will not use this option for the exercise.
(5) The "Permute group" option allows one to improve computation time when more facilities are selected in the starting group than in the destination one. But if this option is selected, 'Limit the spatial analysis to the closest pair time-wise' is not possible. We will not use this option for the exercise.
(6) The option "Output the layer of the paths among selected facilities", if checked, will output a polyline shapefile with all least-cost paths among all the start-destination pairs of points.
(7) The "Enable parallelization" option, if checked, allows the referral analysis to be parallelized on all available CPU/Core that your AccessMod has access to. Using this option can drastically decrease the overall computation time for this analysis.
(8) Select the “Limit the spatial analysis to the closest pair time-wise” option if you want to restrict the analysis and the output table to the closest health facility, in term of travelling time. We will not use that restriction in the present exercise.
...