Costs in the Long-Run Just as some costs are fixed and others are variable so are the inputs, or resources, or, factors of production used by the firm and this has an impact on its short and long run operations. These time periods (the short and the long run) do not refer to specific, chronological time of hours, days, weeks, months or years. Rather they are periods of adjustments. The Long-Run is that time period in which all factors of production are variable i.e. the firm can increase its productive capacity by changing the scale of its operation. For example, if a printing press can only deal with 1,000 sheets per minute then it