I have a dataframe in arcMap 10.0.4 that is of Africa Albers Equal Area Conic PCS. I bring in a census shapefile of WGS 1984 CS and it is projected on the fly. I do 2 things:
I use the calculate geometry option to overwrite the "Shape_Area" field in the census shapefile so that I may obtain the planar measurements of the shape area (i.e. square Km as opposed to Decimal Degrees).
I 'union' an existing polygon grid projected as Africa Albers Equal Area Conic with the WGS'84 Census shapefile. The result of this union is a shapefile with the Africa Albers Equal Area Conic PCS.
I ask both these questions because they seem to me to stem from the same issue: error propagation. Am I creating measurement and geometric errors because I should be instead projecting the census shapefile to Africa Albers Equal Area Conic PCS? What is the capabilites of ArcMap to handle this issue?