EconGuru’s Economic Glossary (reference below) defines variable input as an input whose quantity can be changed in the time period under consideration.
EconGuru goes on to say:
“This should be immediately compared and contrasted with fixed input. The most common example of a variable input is labor. A variable input provides the extra inputs that a firm needs to expand short-run production. In contrast, a fixed input, like capital, provides the capacity constraint in production. As larger quantities of a variable input, like labor, are added to a fixed input like capital, the variable input becomes less productive. This is, by the way, the law of diminishing marginal returns.”
Atlas topic, subject, and course
Economic Glossary, variable input, at http://glossary.econguru.com/economic-term/variable+input, accessed 19 May 2016.
Page created by: Ian Clark, last modified 19 May 2016.