Everyone talks about the “market,” but no one tells us exactly what it is. The Dictionary of Real Estate, 5th ed. Appraisal Institute, defines “Real Estate Market” as “Buyers and sellers of particular real estate and the transactions that occur among them.” Close, but no kewpie doll prize. I have had at least three graduate […]
Why should I care about statistical stuff? Appraisal says: Pick some comps, compare, reconcile, and give a number. No statistics there. Data science says let the market pick the data, predict, and provide a reliability score. Traditional appraisal and modern data science have the same goal: help make decisions by analyzing data. Statistical thinking is […]
Judgment versus science. Judgment wins! (Part I of “Data Collection”) I have heard such things as “No science formula will ever replace my experience and training.” And “no AVM (Automated Valuation Model) will ever inspect a house.” Judgment wins. Except for one problem. The market share of valuations continues down for appraisers. AVMs, ‘evaluations’, broker […]
We clean, scrub, transform, wrangle, munge, map, shape, enrich, enhance, prepare, preprocess, improve, and … verify. Data scientists spend 80% of their time on the data. Those of us who continue to move into these more objective methods – find this to be true. In fact, once you have the data prepared and enhanced, the […]
“Ya gotta make this stuff simple” I am told . . . Data Science: Get the right data, clean the data, apply predictives, get results. Property analytics: Get the right data, clean it, apply predictives, get results. So let’s expand this: Step 1. Identify the problem, download all the data you will ever need. Step […]
Hairy scary hybrid parry. Let’s look deeper, now that we seem to be away from the original hype. When this thing first came up from the GSEs (FannieMae and FreddieMac), a hybrid appraisal was narrowly defined. Basically, it separated the desk job from the field job. I was even in a room once where the […]
Graphs for analysts and appraisers are how we see. It is difficult to vision a median or clusters or market relationships using just numbers. It is even blurrier when someone uses p-values, R-squared’s, and t-scores, claiming these somehow ‘support’ their personal opinion of value. Bad enough in regular work. Even worse gobbledygook when used as […]
Appraisers study some economics. Data training is “pick comps carefully.” AVMs use data. AVMs (Automated Valuation Models) usually use a lot more data, even dozens or hundreds or …. Appraisers usually pick six or seven comps, based on good judgment and training and experience. We are told comparables should be similar and competitive, so they […]
Cognitive dissonance is the mental stress we feel when we’re confronted with conflicting beliefs and requirements. How could this possibly be a USPAP issue? USPAP, (Uniform Standards of Professional Appraisal Practice) may cause psychological dissonance in appraisers – because the review standards and practice standards have different requirements! For the appraiser, Standard 1-2(h) requires results to […]
It’s not me, I’m not biased! Is it me, the model, or the data? A great problem with legacy appraisal is that bias is about personal bias, rather than analytical bias. USPAP (Uniform Standards of Professional Appraisal Practice) only addresses human bias. Similarly, The Appraisal of Real Estate by the Appraisal Institute only addresses analytical […]
I have been accused of using new big words, when old little ones would do! Yes. Guilty. Why? What is the context? What are the goals? What is the path to the goals? The context is that most readers of these blogs are appraisers or collateral/risk people. The context is also that all related financial […]
In this Part II, (see Part I here) we will reduce the comparison to the component comparable parts. Appraisal: Pick comps. Make adjustments. Opine a number. Data Science: Identify data. Clean the data. Run predictive algorithms. Similar huh? Well – yes and no. Let’s look around. We begin with the beginning: What questions do we […]
Data-driven is a buzz phrase. It can be useful. It can be counterproductive. “And in this corner we have . . .” It’s the appraisers versus the quants in the boxing ring. It turns out that people who are experts in a subject-matter field (appraisers for example) tend to discount the words “data-driven.” The experts […]
Take a sample or pick comps: different or the same? Most of us grew up first learning descriptive statistics: mean, median, standard deviation and such. Later, we learned that it was usually impossible or too expensive to get all the data, so we got a sample which seemed to be like the whole ‘population’ we […]
There will soon be no need for residential appraisers. I remember years ago, doing education for my merging AIREA/SREA chapter(s) in San Diego. AVMs were just coming to our attention. I invited a MAI who happened to also be a PhD in economics, Phil Mitchell. The room was full. Someone asked about those “automated algorithmic […]
