Decide at the margin

The idea

Marginal analysis compares the additional benefit and additional cost of a small change. A project can be worthwhile overall while its next increment is unattractive. Conversely, an imperfect existing program may still benefit from a carefully chosen additional unit of effort.

Worked example

A local archive has already digitized its most requested records. The next batch costs 300 units and is expected to avoid 100 units of manual retrieval work. Another batch, from a frequently requested collection, costs 200 and avoids 400. The earlier success of digitization does not justify every new batch. Staff rank the available increments and select the frequently requested collection, while keeping public access benefits visible alongside administrative savings.

Use it carefully

Marginal comparisons depend on the size of the proposed change. Adding one hour of service may require overtime; adding ten hours may require another employee and alter costs discontinuously. Also ask whether benefits interact across increments. A collection with incomplete metadata may become useful only after a whole set is processed. Use marginal reasoning to clarify a decision, then check thresholds and dependencies.

RETRIEVE. REASON. REMEMBER.

Knowledge check.

Choose one answer for each question, then check your reasoning.