Relevant Range
Managers should never forget that variable and fixed cost-behavior patterns are valid for
linear cost functions only within a given relevant range. Outside the relevant range, variable
and fixed cost-behavior patterns change, causing costs to become nonlinear (nonlinear
means the plot of the relationship on a graph is not a straight line). For example,
Exhibit 10-2 plots the relationship (over several years) between total direct manufacturing
labor costs and the number of snowboards produced each year by Ski Authority at its
Vermont plant. In this case, the nonlinearities outside the relevant range occur because of
labor and other inefficiencies (first because workers are learning to produce snowboards
and later because capacity limits a