## I spent \$25,000, and my pool is worth how much!?

Sometime back a Realtor acquaintance called to ask how much to adjust for a swimming pool. The question implied that we appraisers have access to some kind of secret “book” in which we maintain the dollar amounts of our various adjustments. Would that this were true! I explained to the Realtor© we had to extract our adjustments from market data. The parting comment was something along the lines of, “Well, that would take too long!” And our conversation ended. So, let’s talk about that.

It’s not particularly difficult to calculate a swimming pool adjustment. This can be done by paired-sales analysis or by regression analysis. While I prefer regression analysis, both produce perfectly acceptable results. The results are acceptable not because one or the other is “right” or “correct”. Rather, they are acceptable because the adjustment comes from the market, which must be the source of all of an appraiser’s adjustments. So let’s consider a hypothetical paired-sales analysis to extract a swimming pool adjustment from the market.

Take 10 sales more-or-less comparable with the subject that have swimming pools, and then compare those with 10 sales more-or-less comparable with the subject that do not have swimming pools. You’ll probably end up with 10 indications of the contributory value of a swimming pool. Next, arrange the differences from low to high. Take a look at this range. If there are one or two numbers that are obviously outliers, delete them. Now consider this range to determine if there is a central tendency. For example, is there a contributory value indication that repeats itself? This would be a modal value. Is there a range of contributory values that repeats itself? If so, somewhere within this range is the likely contributory value of the swimming pool.

Look at the average and median differences as well. Frankly, you probably want to avoid the average contributory value because of the inherent differences there are in swimming pools. An average weights all of the numbers in the array the same. Since the market likely does not do this, it’s best to avoid it. The median value represents the absolute middle of the range, but is not affected by extremes or outliers.

You started out with a rather wide range of contributory values, but via the above analyses you have likely narrowed it. This narrowing process is exactly what you’re looking for from paired-sales analysis.

Suppose that your analyses indicated a reasonable range from \$10,000-\$15,000. Out of this range you are going to choose your adjustment (even though a range is far more indicative of the market’s thinking). Also suppose that the swimming pool at your subject is relatively “plain vanilla”. For this reason, you would probably go with the low end of the range, say \$10,000. On the other hand, were your subject swimming pool rather ornate, large, and/or came with an overly large patio and pool deck area, you would probably go with the higher end of the range (although, that would be your judgment call).

The point here is that you did not “guess” at the contributory value of that pool, etc. You did not try to cost out a pool as if new and then apply a depreciation factor. You did not apply a “rule-of-thumb” to determine your adjustment. Rather, you went to the market and, via analyses of the available sales within a market comparable to that of the subject, teased out of it a reasonable approximation of the contributory value of the swimming pool.

Please understand that the best you can do is approximate the contributory value of the swimming pool. This is because individual buyers and sellers react to such an amenity differently. As a result, your adjustment of, say, \$10,000 does not mean the market sees the contributory value of a pool to be merely \$10,000. Via your analyses, you demonstrated that the market sees a range of contributory values. From that range you, the appraisal expert, concluded that an adjustment of \$10,000 approximated the contributory value of the swimming pool at your subject.

In other words, you supported your conclusion. This is all a client can ask for. Your client may not agree with your conclusion. However, your client must agree that your adjustment is based on logic, reasoning, and market evidence. That’s really the best you can do.

So, the point here is, while you may not be able to prove exactly how much a swimming pool contributes to the market value of a specific property, you can show the range of that value. Then, from it, you choose an individual number, even though that range makes more sense in the market. It’s your opinion that the swimming pool at the subject contributed \$10,000 to overall value. You base your opinion on market data, therefore your opinion is well-formed. As such, you have formed an independent, impartial, objective, and credible opinion of the contributory value of that particular amenity. That’s what appraisers do.

## Complexities

Complexities in appraisal work come up periodically, depending on the market you work in and the types of properties that are common to the area. I office in Colorado and have had the opportunity to appraise in rural and extremely remote areas. In the case of one particular market area, the trip one-way takes over two hours and is over 1,500 square miles; in this particular market, you’re lucky to have 30 sales over any two-year period – and that’s counting all residential properties, whether on a lot in town or a large-acreage parcel, a 90-year-old small house or a custom log house. You can bet there are complex assignments in this area. However, it doesn’t take a remote area to result in complex appraisal assignments.

Typically, complexities originate from two sources:

1. Physical or locational characteristics of the subject property itself, and/or
2. Limited sales or uniqueness in the area.

Complexities are a double-edged sword. If you only have two dozen sales in the entire area over a multi-year search period for selecting comps, and your subject is not located in a subdivision, you have to decide whether the glass is half-full or half-empty. Likely, there is no “model match” to your subject; however, you don’t have too many sales to sift through to choose which will give the best perspective in evaluating the subject’s value.

An appraiser doesn’t need to cover rural markets to experience similar dilemmas. All it might take is that 3,000 square foot GLA over-improved house in a subdivision of 1,500 square foot GLA houses, or the house with an indoor pool in the area with only starter houses, to appreciate that complex assignments area a test of our appraisal abilities.

But complexities are not an automatic reason to decline an assignment. Let’s be sure we’re prepared!

## USPAP Compliance and Desktop Appraisals

Many appraisers are worried that a so-called desktop appraisal will not be USPAP compliant if a third party to inspects and/or photographs the subject property.

USPAP does not make an issue of who inspects the property, nor who photographs it. USPAP does not require the appraiser to inspect the subject property. Nor does USPAP require the appraiser to photograph the subject property or the comparables. USPAP requires the appraiser to disclose the extent of the inspection of the subject property, which includes no inspection at all. Further, USPAP makes no mention of the need to include photographs of the subject as part of the formation of a credible value opinion. Both these requirements are a function of lender requirements, not USPAP.

Fannie Mae requires the appraiser to inspect the subject property, as well as to inspect the comparable property from at least the road in front of the it (assuming that’s possible). However, Fannie Mae has no requirements the appraiser take these photographs. In other words, a contractor the appraiser hires to take photographs could do this and the report would still be fully Fannie Mae, as well as USPAP, compliant.

An individual lender may require the appraiser to take the subject and comparable photographs him- or herself. If the appraiser agrees to this condition, then the appraiser has no choice but to do so. However, the key point here is that the appraiser personally taking the photographs of the subject and/or the comparables is a lender requirement, not a requirement of USPAP, and not necessarily a requirement of Fannie Mae.

Therefore, under certain conditions, an appraiser doing a desktop appraisal is perfectly USPAP compliant.  Providing photos is not significant appraisal assistance. The appraiser is under no ethical obligation to disclose the photographer’s name, nor the extent of his/her assistance.

## Lies, Damn Lies and Inadequate Sample Size

Benjamin Disraeli was the Victorian era Prime Minister of the United Kingdom.  He famously said “there are three kinds of lies: lies, damned lies and statistics”.  He died in 1881.  This was after Sir Francis Galton coined the term standard deviation, but before he popularized concepts like of correlation and the Central Limit Theorem with his publication of Nature in 1889.

Perhaps Disraeli was witness to how misleading statistics could be without an understanding of sample size requirements.  Most people wander about in the same fog that engulfed Disraeli.

The Central Limit Theorem states that a sample size equal to or greater than 30 is required to make credible assertions about a population.  “In practice, the Central Limit Theorem allows us to make inferences about population means relying on the normal distribution when a) the population is normal or b) when n ≥ 30. As a practical matter, the sampling distribution of the mean will be approximately normal when n ≥ 15 and the population is symmetrically distributed. However, appraisers usually know very little about the shape of population distributions of price, property attributes, financing arrangements, and the like. Therefore, the n ≥ 30 criterion generally applies to real property valuation work.”[1]

In general, if the mean and the median of a population differ, the distribution is not normal and you need a sample size of 30 or greater.

[1] Marvin L. Wolverton, PhD, MAI, An Introduction to Statistics for Appraisers (Chicago, The Appraisal Institute)