Home buying, with a dash of instrumental rationality

Before I go on, let me digress by calling attention to this fascinating paper, the abstract of which I reproduce below:

This study examined the relationship between near-home nature and three forms of self-discipline in 169 inner city girls and boys randomly assigned to 12 architecturally identical high-rise buildings with varying levels of nearby nature. Parent ratings of the naturalness of the view from home were used to predict children’s performance on tests of concentration, impulse inhibition, and delay of gratification.

Regressions indicated that, on average, the more natural a girl’s view from home, the better her performance at each of these forms of self-discipline.

For girls, view accounted for 20% of the variance in scores on the combined self-discipline index. For boys, who typically spend less time playing in and around their homes, view from home showed no relationship to performance on any measure.

These findings suggest that, for girls, green space immediately outside the home can help them lead more effective, self-disciplined lives. For boys, perhaps more distant green spaces are equally important.

Moving on, then.

Call an agent “rational” if it wields its intelligence in such a way as to maximize the convergence between its beliefs and reality; and acts on these beliefs in such a manner as to maximize its chances of achieving whatever goals it has. (For humans, this means among others mitigating the effects of cognitive biases.)

There are two kinds of rationality:

Epistemic rationality involves achieving accurate beliefs about the world. It involves updating on receiving new evidence, mitigating cognitive biases, and examining why you believe what you believe.

Instrumental rationality is concerned with achieving goals. More specifically, instrumental rationality is the art of choosing and implementing actions that steer the future toward outcomes ranked higher in one’s preferences. Said preferences are not limited to ‘selfish’ preferences or unshared values; they include anything one cares about.

Here’s a nice post on instrumental rationality as applied to buying a home:

“A new house is one of the most important purchases most people will make. Because of the sums involved, the usual pitfalls of decision-making gain new importance, and it becomes especially important to make sure you’re thinking rationally. Research in a couple of fields, most importantly positive psychology, offers some potentially helpful tips.


People so consistently under-count the pain of commuting when making choices that the problem has its own name:Commuter’s Paradox. The paradox is that, although rational choice theory predicts people should balance commuting against other goods and costs, so that one person might have a longer commute but a nicer (or cheaper) house and so be just as happy overall, this doesn’t happen: people who have long commutes are miserable, full stop. A separate survey by Kahneman and Krueger found that commuting was the least enjoyable of nineteen daily activities mentioned, and other studies have found relations between long commutes and poor social lives, poor health, high stress, and various other problems.

Psychologists aren’t entirely sure why people so consistently under-count the pain of commuting. Maybe it’s because it’s viewed as “in-between” time rather than as an activity on its own; maybe it’s because it comes in relatively short and individually bearable chunks repeated over many years, instead of as a single entity. In any case, unless you are mentally atypical you will probably have a tendency to undercount commute time when buying a new home, and may want to adjust for that tendency.


One of Kahneman and Tversky’s famous bias experiments went like this: imagine you’re buying a new shirt. It costs $40 at a nearby store, and it costs $20 at a store that’s fifteen minutes away. Do you drive the fifteen minutes to save twenty bucks? Most people would.

Now imagine you’re buying a new TV which costs $2020 at a nearby store, and $2000 at a store that’s fifteen minutes away. Do you drive the fifteen minutes to save twenty bucks? Most people wouldn’t.

In both cases, the tradeoff is the same – drive fifteen minutes to save twenty bucks – but people were much more willing to do it for the cheap item, because $20 was a higher percentage of its total cost. With the $2000 TV, the $20 vanishes into the total cost like a drop in the ocean and seems insignificant.

Nice homes can cost $500,000, $1,000,000, or even more. There doesn’t seem to be a big difference in price between $710,000 and $745,000 houses; perhaps if the second home looked even a little nicer in an undefinable way you might be prepared to take it. But $35,000 is $35,000; if those minor advantages don’t provide $35,000 worth of value, when measured on the same scale on which you measure the value of of movie tickets, shoes, and college funds, then you should buy the first house and keep the cash.

I find purchasing decisions easier when I think about them like this: which would you rather have, the second house, or the first house plus a two-week luxury vacation to anywhere in the world every summer for the next five years? The second house, or the first house plus a brand new Lexus? The second house and dining at home every week, or the first house and eating out at your favorite restaurant every weekend for the rest of your life? (EDIT: gjm points out that it’s easier to resell houses than other types of good, so if you expect to resell your house you should really only be considering the extra money involved in the mortgage)


The availability heuristic says that people overcount scenarios that are easy and vivid to imagine, and undercount scenarios that don’t involve any readily available examples or mental images. For example, most people will assert, when asked, that there are more English words ending with “-ing” than with “-g”. A moment’s thought reveals this to be impossible – words ending in “-ing” are a subset of those ending in “-g” – but thinking specifically of “-ing” words makes it easier to bring examples to mind.

The real estate version of this fallacy involves exciting opportunities that you will rarely or never use. For example, a house with a pool may bring to mind the opportunity to hold pool parties. But most such plans will probably fall victim to akrasia, and even if they don’t, how often can one person throw pool parties without exhausting their friends’ interest? Pool parties may be fun to imagine, but they’ll probably only affect a few hours every couple of months. Other factors, like the commuting distance and whether your children end up in a nice school, may affect several hours every day.

(a classic example here is the “extra bedroom for Grandma” – visits from Grandma are easy to imagine, but if she only comes a couple of days a year, spending tens of thousands more dollars for a house with an extra bedroom and bathroom for her is probably pretty stupid. You’d save money – and make her happier – by putting her up in the local five star hotel.)


Good illumination and a view of natural beauty aren’t just pleasant luxuries, but can make important practical differences in your life.

Light, especially daylight, has a strong effect on mood. There are at least fifteen controlled studies showing that bright light reduces symptoms of seasonal and nonseasonal depression by about 10-20% over placebo. This is about equal benefit to some antidepressant drugs, and sufficient that light therapy is a recognized medical treatment for depression.Bright light leads to self-reported better mood even in subjects without a diagnosis of depression, and also leads to better sleep and more agreeable social interactions.

Light and nature have positive effects on health. Some of the most compelling data comes from hospitals, which have long realized that their patients near windows do better than their more interior counterparts. In one study, surgical patients near windows recovered faster (7.9 vs. 8.7 days), received fewer negative comments from nurses (1.1 vs. 4 notes), and needed fewer strong painkillers (1 vs. 2.5 doses) than matched controls without a view. Other studies have compared recovery of physiological indicators of stress (for example, blood pressure) in subjects viewing natural or artificial scenes; the subjects with views of nature consistently have healthier stress reactions.

Nature may have special benefits for children. Experiments with subjects of all ages and levels of mental health have shown nature increases mental functioning and concentration, but some of the most cited work has been in children with Attention Deficit Hyperactivity Disorder. Children who live in greener settings also (independently of wealth) do better on schoolwork and show greater ability to delay gratification. Large studies find with high certainty that students who take standardized tests in better lighting do up to 25% better than their literally dimmer schoolmates, and progress through lessons 15-25% faster.

You don’t have to live in the Amazon to get a benefit: even children in a concrete building with a tiny “green island” boasting a single tree did better than their peers in a building without such an island.


Brains generally encode variables not as absolute values but as differences from an appropriate reference frame. That means that to really appreciate your wealth, you’ve got to be surrounded by people who are poorer than you are.

This seems to be empirically the case: a US study found the happiest Americans were rich people living in poor counties. However, this was true only of rich people living in rich neighborhoods of poor counties. As the study puts it, “individuals in fact are happier when they live among the poor, as long as the poor do not live too close”.

Of course, this doesn’t mean that you should move to Somalia for eternal bliss. There are community-wide benefits to living in a wealthy neighborhood, like better schools, and you may be better able to socialize with people from a similar class background as yourself. But given the choice between a neighborhood at the top of your price range and one at the bottom, you may find yourself more satisfied living in an area where it’s the Joneses who have to try to keep up withyou.


It’s easy to confuse “rationality” with a tendency to turn all decision-making over to conscious general-purpose reasoning, and in turn to assume that whoever ruminates about a decision the most is most rational. But there are at least two reasons to think that within reason it may be better to worry less over important decisions.

One is the finding that “comparison shopping” usually leads to less happiness in whatever you buy. Imagine being pretty sure you’re going to buy House X until you look at House Y and find out that this one has a granite fireplace, and a pond in the backyard. It may be you don’t like House Y at all – but now every time you go back to House X, you’re thinking about how it doesn’t have a granite fireplace or a pond, two features which you never would have even considered before. Whether you find this explanation plausible or not, the research generally agrees: too many choices result in less satisfaction with whatever you finally buy.

The second is the discovery that attempts to make your reasoning explicit and verbal usually result in worse choices. This includes that favorite of guidance counselors: to write out a list of the pros and cons of all your choices – but it covers any attempt to explain choices in words. In one study, subjects were asked to rate the taste of various jams; an experimental group was also asked to give reasons for their ratings. Ratings from the group that didn’t need reasons correlated more closely with the ratings of professional jam experts (which is totally a thing) than those who gave justifications. A similar study found students choosing posters were more likely to still like the poster a month later if they weren’t asked to justify their choice (Lehrer, How We Decide, p. 144).

The most plausible explanation is that having to verbalize your choices shifts your attention to features that are easy to explain in words (or perhaps which make good signaling value), and these are not necessarily the same features that are really important. In a telling experiment under the same protocol as the ones listed above, people asked to reflect upon their choices were more likely to choose the house with the extra room for Grandma than the house with the shorter commute times, because the extra reflection gave more opportunity for the availability heuristic to come into play.


Buying a house is one of the biggest decisions a family faces, and so has extra opportunity to be improved by rational thinking. Try to buy a house with good illumination and nearby green space in an area close to your workplace where you’ll be relatively high on the social ladder. Carefully consider whether special features have genuine utility or are just highly available small details, and justify the relative differences in cost in absolute, not just relative terms.”


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