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Cost engineers in industry use a very simple model based on factors of man-hours of labor per unit of production. The factors are based on experience. The use of predetermined time and motion studies requires a finished engineering design and a methods study.


e = man-hours per unit of the process, p, being performed, in Earth environment

F = factor by which e will be increased or decreased

for the process, as a function of location

p = manufacturing, extracting, or erecting process being evaluated

W= quantity of the end product in production units

I = location at which the process will be carried out

= man-hours required to produce W units of production by the process, p

E = man-hours required for some finished structure or unit.

Then for any process and any location,

= WeF

and for any finished structure or unit,

The model makes possible a labor estimate at any stage of design, simply becoming more detailed as to operations and factors as the design becomes more firm.

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