Fertile Variables and Rich Moves

Engineers and others attracted to comprehensive systems views often fail in a predictable way: they translate all their objectives into multi-factor optimization models and trade-off curves which then yield spectacularly mediocre results. I commented on this pathology as part of a recent answer to a question about choosing among multiple job offers on Quora  and I figured I should generalize that answer.

Why is this a failure mode? Optimization is based on models, and  this failure mode has to do with what you have left out of your model (either consciously or due to ignorance or a priori unknowability). If there are a couple of dozen relevant variables and you build a model that uses a half-dozen, then among those chosen variables, some will have more coupling to variables you’ve left out than others. Such variables serve as proxies for variables that aren’t represented in your model. I’ll overload a term used by statisticians in a somewhat related sense and call these variables fertile variables. Time is a typical example. Space is another.  Money is a third, and particularly important because ideological opinions about it often blind people to its fertile nature. Physical fitness is a fourth.

Fertile variables feed powerful patterns of action based on what I will call rich moves. 

Rich Moves

In complex situations, where you suspect you’ve left out more than you’ve included in your models,  it is very useful to decide what to do purely in terms of fertile variables, maximizing or minimizing them in some way. This goes against the instincts of most modelers, who want to build complicated multi-factor formulas based on multivariate models.

A move based primarily on manipulating a fertile variable while neglecting others is what I call a rich move.  The prototypical example from which I derive the term is to decide you simply want to get rich, no matter how, and ignoring other aspects of a “well-rounded” life.

This is because if you succeed in this “rich” move, other problems will tend to sort themselves out. Once you are rich for example, you can hire a personal trainer and personal chef to take care of your health. And this is not just an arrival fallacy of the “life will be better once I am rich” sort. I know many rich people who’ve done exactly this, and are now healthy and happy. Yes, money can buy happiness if used properly. It is a fertile proxy variable for most variables involved in the murky and hard-to-model idea that is happiness. There is plenty of research showing that money does not increase happiness beyond a point, but I suspect that’s because most people don’t know how to use it. I know enough rich people who are far above the “happiness plateau” threshold (about $60,000 or so in income per year in the US if I recall correctly; I forget where I heard the figure) and also much happier than regular 60k/year schmucks, because they know how to deploy the money very effectively (so it is partly a matter of spending skill, which most of us don’t acquire because we don’t get enough practice).

Another example, if you are in the technology sector, is deciding to move to San Francisco. It moves one variable (or rather 2: latitude and longitude) without much thought to other variables like cost of living, closeness to markets and so forth.

How Rich Moves Work

In formal mathematical modeling, you often start with higher-order models involving dozens or even hundreds (in the case of computer-aided models) of variables and reduce them to lower-order ones using  systematic techniques (if you are interested, they have names like “balanced model order reduction” and involve advanced mathematical techniques such as singular value decomposition).

But far more often, your modeling uncertainty is unknown-unknown. You don’t know what you left out, let along consciously and carefully doing the pruning.

For such situations, the behavior of your model in practice will yield hints about what you don’t know, because some variables will seem to have impact beyond what your model predicted.

The key to identifying and pursuing action patterns built around rich moves is to resist the temptation to maximize learning. The actions that help you learn fastest (and therefore build out and complicate your model the fastest) are generally not the same as the ones that help you gain rewards fastest. The reverse is often true. Rich moves may allow you to further simplify the models you already have.

Rich moves, rather than maximizing learning, herd the most variables into positive regions. Moving to San Francisco also gets you good weather, great food, close access to great natural beauty, a good deal of cultural diversity, other talented people, great universities and so forth. Yes, you also get earthquake risk and a certain amount of groupthink and cultural smugness, but overall “move to San Francisco” moves far more variables into the right regions than into the wrong regions for someone who wants to build great technology.

On the other hand, if you want to actually understand how the world of technology works (learn the best possible model), spending too much time in San Francisco can be very dangerous. You go to San Francisco to get rich off technology, not to understand it better. This is one reason I’ve not (well, not yet anyway) moved to San Francisco. I am more interested in understanding technology than getting rich off it. I’ve found some of the best insights into the nature of technology in strange and obscure corners of the world.

Common Examples

Here are some common examples of fertile variables and rich moves:

  1. In physical fitness, treating each muscle as a variable, a few are far more fertile than others (chest, back, thighs) and exercising them using rich moves (benchpress, military press, squats) yields dividends far faster than other more complicated moves.
  2. In jobs, your manager is a fertile variable (based on Gallup research). If you have a great relationship with a great manager, most other problems will sort themselves out. So a rich move is to find a job where you’ll be reporting to a great manager.
  3. In life in general, money is a rich variable, as I’ve already said. But due to its artificial nature, it comes with many weird traps that you have to be wary of.
  4. In decision-making, tempo is a fertile variable. While driving tempo up is not always a bright idea, generally iterating faster improves a lot of things.
  5. In healthy eating, proteins and green vegetables appear to be rich variables, but I am a little bit more doubtful here, and don’t know enough to make strong claims.
  6. In the world of languages, knowing English is a fertile variable. Moving to an English-speaking country is a rich move. Or used to be.
  7. In mental development, some (appreciative, not just manipulative) knowledge of college-level mathematics is a fertile variable. People who know a certain amount of mathematics in the right way, generally think better on all questions, including ones involving no mathematics (the pathology I pointed out at the start of this post is the sort of danger that mathematical knowledge can bring; the key is to develop an appreciative understanding of mathematics alongside a manipulative one). A fertile move for any student is to move to an environment with a lot of good mathematics in the environment. So educational settings that lack mathematics are dangerous.

What other fertile variables and rich moves do you know of?

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About Tempo


  1. In social life, adopting a “no asshole” rule. Anyone who treats you poorly you avoid. Like the William Gibson quote — “Before you diagnose yourself with depression or low self-esteem, make sure you are not, in fact, just surrounded by assholes.”

    Also, a persistent somewhat irrational belief that things will “work out” makes it much more likely that that things will actually work out in your favor as you first have to convince yourself something is possible before you’ll actually make the effort to make that thing a reality. Faith before works and so on.

  2. Network comes to mind. If you know a lot of the “right” people, a lot of other things will work out much more easily.

    In many fields there are similarly certain techniques that are “rich” in a similar sense, that if you know them, you will approach the problems in a way that is likely to work out right most of the time. For example, developing web-applications with an RDMS backbone used to be one of these techniques (while it isn’t perhaps anymore), and a basic course on algorithms and data structures was perhaps the only thing you needed to do to have a successful career. In machine learning I would argue that classification is a rich technique.

    The problem with these techniques is that they are hard to identify from the beginning rather than in retrospect, as I am now doing. Any suggestions for that? Perhaps studying successful people and mining for techniques?

  3. Alexander Boland says

    A few ones that I’d put down:

    1) For those who have trouble with their sex life–doing what it takes to become more attractive and better at social interaction is a rich move. Feelings of social inadequacy are very damaging to one’s mental and physical health, and besides which, who wants to be miserably celibate? A big push is justified in that scenario.

    2) Pursuing your “dreams” at full steam. As long as you can hedge against catastrophe, you have much more to gain by being pushed to your absolute limit than by sitting around and waiting for the supposed opportunity on its way.

    3) Learning how to manage without pharmaceuticals. I confess that I have not entirely accomplished this, but I am a lot less fragile since I’ve been able to cut down my need for asthma medications by 90%. Amazingly, no doctor had the sense to tell me the few simple breathing tricks that did it.

    4) Intermittent fasting. Between the religious rituals, apocryphal evidence, lab experiments, and theoretical science, there seem to be an explosion of positive unknown-unknowns that come from practicing it (no wonder Taleb is into it.) I can’t be 100% confident though, and if you have any health conditions, please consult a doctor.

    5) Making “no excuses”. Before you pass this off as a cliche, what I mean to say is that if you do something that binds you to a no-excuses policy (like a monetary wager), you may end up losing out a bit when you have a legitimate reason, but you’ll easily make up for it with all the times where you ignored bogus reasons.

    6) Sleep. As Tim Ferriss put it, it’s the ultimate force multiplier.

    7) Finally, two bonuses. Bonuses because they’re concepts rather than specific things: first, life begins where your comfort zone ends. Second, ask yourself if what you’re doing can return compound interest.

    • Alexander Boland says

      Actually, change (5) to “crossing the rubicon”. Easier to just frame that whole thing in terms of saying “the die has been cast.”

  4. Vinod Khare says

    Are there any general rules for identifying fertile variables?

    • I’d say they are generally a ubiquitous and background variable to all activities. For example “space” (coordinates) is an element of everything. Sleep, which Alexander mentioned, is 1/3 of every day…

  5. Vinod Khare says

    Does the middle class financial script (http://www.ribbonfarm.com/2011/12/08/acting-dead-trading-up-and-leaving-the-middle-class/) fail in precisely this way? The question on quora intuitively appears to be a very middle class question to ask. The rich or the poor would automatically *know* what (fertile) variable to optimize for.

  6. That sounds very close to Gerd Gigerenzer:
    A more intricate model isn’t necessarily better and certainly most costly.

  7. “Moving to an English-speaking country is a rich move. Or used to be.”

    LOL, I’d like you elaborate on that (sometimes…)

    • Well, the tweet-sized answer is that you and I are conversing right now in English rather than French or Hindi. The leverage of English is enormous. Mandarin might be that way within 30 years (but for a different kind of leverage, not scope of coverage… I don’t think everybody will learn Mandarin, it is too difficult a language) if America genuinely declines.

    • Alexander Boland says

      Kyle, that’s a great one. It’s actually in many ways generalizable to the strategy of pumping up a single variable in order to get non-linear benefits (known also as the “barbell” strategy).

  8. Fertile Variable: attention/concentration; with the practice of meditation as the associated Rich Move. Two of the most common types of Buddhist meditation, concentration (holding a single object, such as one’s breathing, as uniformly and completely in one’s mind as possible) and insight (dialing into the transience of reality by an almost hyperactive awareness of whatever fleeting sensory input or mental activity is at the forefront of one’s mind), have pretty wide-ranging potential to facilitate lifehacking. If a genius is defined (via Keynes, a la Newton) by the “power of holding continuously in his mind a purely mental problem” the application of the first is pretty obvious, while the second makes conscious the subtle mood and tempo changes that subconsciously affect you. If for instance you regularly get stuck on problems when your blood sugar levels are lowest, you might realize that rather than the problem causing your frustration the converse holds, and get a snack. Together these two will jumpstart metacognition; if something like increasing your grip on appreciative mathematics is an improvement of your mental algorithms, practicing meditation is hacking your compiler.

    • Alexander Boland says

      Very true, makes me think of something a lot of intelligent critics have said: that school’s #1 task it to teach us to concentrate. Concentration, self-control, willpower; these things are perhaps the most fertile variables out there.

      I meditate twice a day, though not in either of the ways you said. It does help me concentrate, but for the most part it’s a rich move because it restores energy, calms me down, and has gotten me out of god knows how many daily ruts. A very rich move indeed.

      • I am sympathetic to this candidate fertile variable, but it is in general too… well, general. I prefer specific instances like ‘mindful eating’ below for the purpose of analyzing leverage in a given domain (health in this case). This is like saying “being good is a fertile variable.”

  9. micheal vassar says

    I think non-processed food or eating attentively may also be rich variables in food, possibly richer than protein or vegetables.
    It’s possible, IMHO, that coding is richer than math.
    In life in general, I think that self-awareness is much richer than money, but harder to come by. Courage may also be richer than money.

    • Coding richer than math. Hmm… very interesting idea there. Not sure it is now, but I think in future it will increasingly be the case.

      Self-awareness, courage, mindfulness… my general problem with these is that they are too general. I am thinking of variables that manifest much more explicitly. More rubber-meets-the-road variables.

      One way to distinguish them is to distinguish between environmental leverage (moving to San Francisco) and mental leverage. The former is much more legible in its effect, though the latter may be more important.

  10. Could you distinguish between RichMoves and RulesOfThumb or heuristics?

    • A rule of thumb is a procedural shortcut that does nothing beyond what is advertised. Like the Rule of 72 for compound interest. It usually simplifies a commonplace default case of a general problem.

      A heuristic is a similar looser notion that is probabilistic in terms of nature or quality of outcome. Like FIFO as a scheduling heuristic. Under favorable conditions it is near optimal in useful ways.

      A rich move may be either an exact or heuristic/rule-of-thumb solution to a nominal problem, but is “rich” due to its positive, unpredictable, unintended consequences.

  11. Regarding money and happiness:

    “If money doesn’t make you happy, then you probably aren’t spending it right.” Dunn, E. W., Gilbert, D. T., & Wilson, T. D. (2011). Journal of Consumer Psychology, 21(2), 115–125. doi:10.1016/j.jcps.2011.02.002

    That more money don’t tend to make people happy is one of the classic results in the field. That people don’t know what makes them happy is another. Why noone has put the two together before is a mystery to me.

  12. I’d definitely agree with the observation about learning vs success:

    If these moves primary advantage is to reduce complexity, to get two for the price of one, then their very effectiveness will wash out the effects of other variables.

    It occurs to me that there could be variables that are the inverse of this, that rather than effecting other variables associated with success, are actually common side effects of multiple different variables.

    Depending on your maximisation strategy, this could be fine, as a sort of totemic strategy; “maximise a value and everything correlated with it”, might still hit the significant factors, whereas a trade-off based maximisation strategy “whenever you have a choice, choose the one that most directly improves the main variable” would likely fail.

    My suspicion is that money has elements of both a dominating variable and a common side effect, and fame is a strong example of the latter, unless you follow specific fame into fame strategies.

  13. Alexander Boland says

    Going back to this, isn’t the fertile variable really another way of talking about the schwerpunkt? It also seems to underlie the notion of “optionality” in NNT’s “barbell heuristic.”

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