Sales Comparisonhard16.4% of exam

Adjusting site size in a market where lots run 8,000–12,000 sq ft, using a per-square-foot land rate from vacant lot sales, tends to overstate the adjustment because:

Correct Answer

D) Extra land contributes at a diminishing rate once the site is adequate

Why this is correct: Land value per square foot typically diminishes as lot size increases beyond what the market considers adequate for the improvement type. Using a per-square-foot rate from vacant lot sales ignores this diminishing marginal utility and overstates the adjustment. Why the other choices are wrong: 'Vacant lot sales are always recorded at inflated prices by sellers' is wrong; this is an unsupported generalization. 'Land prices per foot are fixed by the assessor's schedule of values' is wrong; assessor values are not market-derived adjustments. 'Site size never affects the price buyers are willing to pay at all' is wrong; site size does affect value, but not at a constant rate. Exam tip: Site adjustments are best derived from paired sales of improved properties.

Answer Options

Vacant lot sales are always recorded at inflated prices by sellers

Land prices per foot are fixed by the assessor's schedule of values

Site size never affects the price buyers are willing to pay at all

Extra land contributes at a diminishing rate once the site is adequate

Why This Is the Correct Answer

Option D is right because extra land contributes at a diminishing rate once the site is adequate for its intended use, and every lot in an eight-to-twelve-thousand-foot market is adequate. That diminishing contribution is precisely what a whole-lot average rate fails to capture. The appraiser's remedy is to extract the incremental rate from improved sales that differ mainly in lot size, then apply that smaller figure to the size difference. Stating the reason this way also gives the appraiser something defensible to write in the report, which is what a reviewer will look for.

Why the Other Options Are Wrong

Option A: Vacant lot sales are always recorded at inflated prices by sellers

Sale prices are verified, not accepted on a seller's say-so, and a blanket claim that vacant lot prices are inflated has no support. Recorded consideration can be distorted in specific transactions by concessions or non-arm's-length relationships, which is exactly why verification is part of the approach. A generalization about an entire data category is not analysis.

Option B: Land prices per foot are fixed by the assessor's schedule of values

Assessor land schedules are mass appraisal products developed for equity and administrative efficiency, not market-derived adjustments for a single property, and they frequently lag the market. Nothing about them fixes a per-foot rate for appraisal purposes. Borrowing an assessment figure in place of a derived adjustment substitutes someone else's model for the appraiser's own analysis.

Option C: Site size never affects the price buyers are willing to pay at all

Site size plainly affects price; buyers pay more for larger lots, which is why the adjustment exists at all. The problem is the shape of the relationship, not its existence - contribution rises with area but at a decreasing rate. Choosing this option throws out the adjustment entirely instead of correcting its magnitude.

Adequate is the pivot

Ask one question of any lot: is it already adequate for what stands on it. Below adequate, area is precious and the rate is high. Above adequate, area is amenity and the rate collapses. Adequate is the pivot where the curve bends.

How to use: When a stem gives you a narrow band of lot sizes, read that as a signal that every lot is adequate and the marginal rate is low. Choose the diminishing contribution answer and reject explanations that attack the data or deny that size matters.

Exam Tip

Distinguish this from a market where a size threshold unlocks a different use, such as a second dwelling or a split; there the marginal foot can be worth more than the average, not less.

Common Mistakes to Avoid

-Using a vacant lot rate for an incremental size difference between improved properties
-Assuming a constant per-foot relationship across the size range
-Substituting an assessor's schedule for market-derived support
-Missing the opposite case where extra area crosses a threshold and unlocks additional use

Concept Deep Dive

Analysis

This question asks for the reason behind the overstatement rather than the fact of it, and the numbers in the stem are doing work. A market where lots run eight thousand to twelve thousand square feet is a market where every site is already adequate for the improvements being built; nobody in that range is buying land to unlock a use that a smaller lot would prevent. Within such a band, the additional area between one lot and the next is pure amenity, and buyers pay for amenity at a much lower rate than they pay for the buildable site itself. A per-square-foot figure taken from vacant lot sales averages in everything a site provides, so importing it into a four-thousand-foot spread charges yard at the price of entitlement. The concept underneath is the principle of contribution: a component is worth what it adds to the whole, not what it costs or what a proportional share of the whole would suggest.

Background Knowledge

You need the principle of contribution, the concept of diminishing marginal returns as applied to land area, and the recognition that a whole-lot per-unit rate measures average rather than incremental contribution. You should also know how to derive a site size adjustment from paired sales of improved properties and why assessment schedules are not a substitute for market-derived support.

Real-World Application

In a subdivision of nine-thousand to eleven-thousand-foot lots, matched pairs show buyers paying roughly one dollar fifty a foot for the difference, while finished lots trade at fourteen dollars a foot. An appraiser who used fourteen dollars on a fifteen-hundred-foot difference would overstate the adjustment by about eighteen thousand dollars.

principle of contributiondiminishing returnssite size adjustmentpaired salesmarket-derived adjustment

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