Adjusting for a difference in lot size using the full per-square-foot land rate typically:
Correct Answer
B) Overstates the adjustment for the extra area
Why this is correct: The value contribution of additional land area typically diminishes (is non-linear). Using the full per-square-foot rate from a small vacant lot sale overstates the adjustment because the extra land may be excess or have less utility. Why the other choices are wrong: It overstates, not understates, the adjustment. It does not produce the correct adjustment. The principle applies to residential and commercial properties. Exam tip: Use paired sales of improved properties to derive a contributory value for extra land area.
Why This Is the Correct Answer
Option B is right because the full per-square-foot land rate overstates the adjustment for extra area. The rate derived from an entire vacant lot represents the average contribution across a site that includes its most valuable attributes, while a size difference between two improved properties involves only incremental yard. The defensible technique is to derive the contributory value of additional area from paired sales of improved properties that differ chiefly in lot size, which measures what buyers actually paid at the margin. Doing so typically yields a rate a fraction of the whole-lot figure.
Why the Other Options Are Wrong
Option A: Understates the required adjustment quite substantially
Understating is the opposite of what happens; the whole-lot rate is the higher of the two figures, so applying it produces an adjustment that is too large. A candidate choosing this has the direction of the error backwards. It may help to remember that the first square foot of a buildable site is worth far more than the ten-thousandth.
Option C: Produces the correct market adjustment
The whole-lot rate produces the correct adjustment only in the unusual case where the market pays linearly for area across the range in question, which is not typical once a site is adequate for its improvement. Treating it as generally correct ignores the distinction between average and marginal contribution. An adjustment method has to be shown to reflect market behavior, not assumed to.
Option D: Applies only to commercial properties
Diminishing contribution of additional area is a general market phenomenon and appears in residential subdivisions as clearly as in commercial districts; if anything the effect is starkest in tract residential markets where lots are close in size. The property type does not switch the principle on or off. Where a commercial site's excess area has independent utility or can be split off, the analysis changes, but that is a surplus-versus-excess-land question rather than a property-type rule.
The first foot and the last foot
A lot's first square foot buys you the right to build. Its last square foot buys you more lawn. They cannot be worth the same, so a whole-lot average rate always overpays for the last foot. Adjust at the margin, not at the average.
How to use: Whenever a question applies a per-unit rate derived from a whole to a difference at the edge, expect overstatement. Choose the overstates answer, and remember the fix is paired sales of improved properties rather than vacant land sales.
Exam Tip
The same average-versus-marginal trap appears with gross living area and with garage bays; ask whether the rate came from a whole or from an increment.
Common Mistakes to Avoid
- -Applying a whole-lot rate to an incremental size difference
- -Assuming linear contribution of area across all lot sizes
- -Failing to distinguish surplus land from excess land
- -Using an assessor's land schedule as a substitute for market-derived support
Concept Deep Dive
Analysis
This question tests the difference between an average rate and a marginal rate, which is where site size adjustments most often go wrong. A vacant lot sale produces an average value per square foot for a whole site, and that figure embeds everything the site delivers - buildability, frontage, access, utilities, and the right to be developed at all. Extra square footage beyond what the market considers adequate for the property type delivers none of that a second time; it delivers only additional yard. So the contributory value of the marginal square foot is lower, often much lower, than the average square foot of an entire lot. Applying the whole-lot average rate to a size difference therefore charges the excess area at the price of prime area, inflating the adjustment. The principle is the same one behind diminishing returns generally: contribution is measured at the margin, not at the average.
Background Knowledge
You need the distinction between average and marginal contribution, the principle of contribution as it applies to land area, and the difference between surplus land, which supports the existing use but cannot be separately sold or developed, and excess land, which can. You should also know that adjustments must be derived from market evidence, with paired sales of improved properties the standard technique for a site size adjustment.
Real-World Application
Vacant lots in a subdivision sell for one hundred twenty thousand at ten thousand square feet, or twelve dollars a foot. Improved sales differing only in lot size show buyers paying about two dollars a foot for the extra area, so a two-thousand-foot difference supports roughly four thousand in adjustment rather than twenty-four thousand.
More Sales Comparison Questions
Excess land differs from surplus land in that excess land:
A paired sales analysis reveals that homes with stainless-steel appliances sell for $2,100 more than identical homes with standard appliances — but only when the homes are priced below $350,000. In the subject’s neighborhood, median sale price is $410,000. What is the appraiser’s obligation regarding the $2,100 appliance adjustment?
GLA differs by 210 sq ft between subject and comparable. Paired sales support $65 per sq ft of living area. The line adjustment is:
Paired sales are drawn from transactions six months apart in a stable market. The time adjustment needed is:
The most appropriate unit of comparison is determined by:
A comparable superior to the subject in every adjusted category should produce an indication that is:
Three sales support $520,000; the borrower's purchase contract is $505,000. May the appraisal conclude above the contract price?
A comparable sold for $300,000 with the seller carrying a loan 2 points below market, a benefit worth $8,000. What is its cash-equivalent price?
Why is a foreclosure sale generally a poor comparable in a stable market?
A comparable sold 8 months ago for $250,000 in a market appreciating 6% per year. What is the time-adjusted price?
People Also Study
Real Estate Market
13.6% of exam
Property Description
11.8% of exam
Land or Site Valuation
4.5% of exam
Cost Approach
13.6% of exam
Income Approach
8.2% of exam