Diagnosis: Cost accounting
• Semi-variable costs (also known as “step variable costs”) are expenses that vary with test volume but not in direct proportion to the volume. Supervisory staffing of the laboratory is a good example; thus, when laboratory volumes increase, a given number of supervisors will be able to handle the increased volume up to a certain threshold. After this threshold is reached, additional supervisors will need to be hired.
• Fixed costs do not vary over time and do not change with sample volume.
• Variable costs vary directly and proportionally with the volume of samples analyzed.
• Costs associated with performing a particular test can be fixed (e.g., the purchase of the equipment needed to perform the test), variable (e.g., the reagents used per test), or semi-variable (e.g., the salaries of the staff required to perform the test).
