Author Archives: sanhei

Food calories are not directly related to obesity

It seems that the change in bodyweight should be a strictly increasing function of calories eaten minus calories spent. The first caveat to this claim is that calories in the food eaten do not equal the calories absorbed, which is what matters for weight gain. People differ in the efficiency of their digestion – that is what bariatric surgery relies on. Also, food labels use calories measured by the burn method (dry the food, burn it, measure the heat output), which ignores for example that coarsely chewed food chunks pass through the digestive tract relatively unchanged, thus contribute few nutrients to the organism. An extreme example is wholegrain flax (linseeds) that remain undigested due to a waxy coating. In nature, seed dispersal by birds relies on the indigestibility of the seeds.

Even if calories absorbed could be accurately measured, the type of food eaten would still matter for weight gain due to imperfect willpower. Some foods are more addictive than others, notably those rich in refined carbohydrates – an easy example is drinks that are essentially sugar-water. Consuming a given amount of calories from high-glycaemic-load sucrose makes people eat more sooner on average than ingesting the same calories from slowly digested whole grains or unsaturated fat. Similarly, ignoring willpower limitations is why abstinence-based programs to prevent sexually transmitted infections, which naively might be expected to be 100% effective, are in fact ineffective (Underhill et al 2007, doi:10.1136/bmj.39245.446586.BE).

There are various tricks to circumvent limited willpower to win the game against one’s future tempted self. To reduce temptation, food should be out of sight outside mealtimes (in cupboards, drawers, fridge) and unhealthy snacks should not be bought at all. Even seeing dishes and cutlery may trigger cravings, in which case these too should be placed out of sight when not in use.

Avoiding grocery shopping while hungry is an old piece of advice, which may be taken further by having someone else buy your food. Two people can even agree to grocery-shop for each other according to shopping lists exchanged beforehand. Online ordering may be a solution, but of course the merchants want customers to buy more, so advertise tempting foods with photos on their website. These ads can be blocked with some effort. A more sophisticated solution is to have one’s own user interface (front end) interact with the merchant’s website – scrape the data on inventory and prices, send commands to buy.

Democracy may be the best system due to political economy constraints

Democracy picks the leader who is best at getting elected, not necessarily the best at leading the country. The ability to become a leader differs from the ability to lead. For example, populism and overconfidence in oneself may help one’s election prospects but harm performance at governing.

Even if there was some very accurate way to select the best leader (e.g. test their honesty, intelligence, work ethic, in addition to electability), it may be not be feasible in practice to make this person govern for long. The reason is the political economy constraint that someone better at obtaining power can depose the best leader (one whose government would maximise social welfare, however defined). The disruption resulting from the coup may even harm society more than the difference between being governed by the best leader as opposed to the best power-grabber. In this case, the leadership of the most electable person may maximise welfare, subject to assumptions like „the best power-grabber is also good enough at retaining power, preventing coups once in government”.

The skills of getting elected and organising a revolution probably differ, so an elected government has some of the same vulnerability as the best leader. The political economy constraint of preventing a coup may then favour making the strongest dictator or the most dangerous revolutionary lead the country. However, this may not be the best system for selecting leaders due to a tradeoff between the ability to govern and the ability to overthrow a government. The welfare-maximising selection system subject to the political economy constraint would pick the person who is best at governing among those who can successfully resist a coup. Democracy may be such a compromise, choosing reasonably popular leaders who have a low probability of being overthrown and are adequate at governing. On the one hand, democracy may avoid a ruthless dictator whose rule is very stable, but harmful, and on the other hand a saintly leader who would be deposed quickly.

Elatustaseme võrdlus ei võta arvesse kvaliteeti

Põhja-Euroopa tomatid on vesised, hapukad ja seest roosakashallid, aga Lõuna-Euroopa omad magusad maitseplahvatused, seest punased. Samuti Gruusias värskelt puu otsast võetud küpsed virsikud ja muud puuviljad on palju maitsvamad kui need, mis on toorelt ekspordiks korjatud ja merekonteineris järelküpseda lastud. Samanimeline restoranitoit Itaalias on palju parem kui Põhja-Ameerikas või Eestis. Erinevate riikide ostukorvi kalliduse arvutamisel loeb aga ainult toodete hind, mitte neist saadav heaolu, nii et elatustase annab heaolutasemest vildaka pildi.

Kui kvaliteet erineks ainult väikse osa ostude puhul (restoranitoit ja puuviljad on keskmise leibkonna kuludes pisike protsent), siis see heaolutaseme võrdlust eriti ei mõjutaks. Üks oluline kululiik, mille puhul kvaliteet riigiti märgatavalt erineb, on majutus. USAs on ka uute kallihinnaliste kortermajade põrandad lainelised, mida kõndides märkab, dušikabiinis jookseb vesi nurka, mitte keskele äravoolu, akna ümber on tuntava tuulega praod ja tänavamüra kostab selgesti. Vanadel ja eramajadel on samad murekohad. Tartus euroremonditud ühiselamus selliseid probleeme polnud, kuigi see oli odav majutus. USAs on ka tippülikoolide hoonetes prussakad ja närilised, Tartus minu teada mitte. Tänavatel on USAs tihti näha kahjuritõrjefirmade siltidega mikrobusse, järelikult selle teenuse nõudlust on. Austraalias on enamik maju soojustamata ka piirkondades, kus kolm kuud aastas on hommikul härmatis maas. Soojustuse puudumisel langes seal mu kütmata kontori temperatuur 12 kraadini ja korteris 10,5ni. Elatustaseme arvutus aga kvaliteediprobleeme ei kajasta, võtab arvesse vaid pinda ja hinda.

Avalike teenuste pakutavat väärtust on statistikas keeruline hinnata, nii et vahel peab piirduma nendele kulutatava rahaga, mis on sisend, mitte väljund. Avaliku ruumi kvaliteet kindlasti riigiti kõigub – tänavate puhtus ja siledus USAs ja Singapuris on nagu öö ja päev.

Kvaliteedierinevuste põhjustatud kallakut ei saa korrigeerida ka avaldatud eelistusi kasutades (Dowrick ja Quiggin 1994 https://www.jstor.org/stable/2117988: kui ühe riigi keskmine elanik saaks teise riigi keskmist ostukorvi endale lubada, aga teise elanik esimese ostukorvi mitte, siis on esimene riik rikkam ja selle elanikud paremas olukorras). Probleemiks on jällegi, et need avaldatud eelistused on ainult hinnapõhised, seega kvaliteeti ei arvesta.

Heaolu sõltub mitte ainult tarbimisest, vaid palju otsesemalt eelistustest. Keskmise elaniku kasulikkusfunktsioon võib riigiti erineda, igatahes stereotüübid sellele vihjavad. Hüpotees eelistuste varieeruvuse kohta on kontrollitav ja Dowrick ja Quiggin 1994 lükkavad selle ümber (erinevusi ei leia), aga nende test sõltub kvaliteedi samasusest riikide vahel. Test seisneb järgnevas ostukorvide võrdluses: kui mõlema riigi keskmine elanik saab endale lubada mõlema riigi keskmist tarbitavate toodete ja teenuste komplekti, aga valitud ostukorvid riigiti erinevad, siis järelikult eelistused kokku ei lange. Eeldus, et mõlema elanikud suudavad osta mõlemat komplekti, on oluline selleks, et sissetulek valikut ei piiraks. Selline rahaline piirang viiks erinevale tarbimisele ehk näilisele erinevusele eelistustes.

Kui mõndade toodete ja teenuste kvaliteet on parem ühes riigis, teistel teises, siis oleks loogiline, et inimesed valivad riigiti erinevad ostukorvid isegi täpselt sama sissetuleku ja eelistuste puhul. Üks võimalik põhjus, miks Dowrick ja Quiggin 1994 sellist erinevust ei leidnud, on et kvaliteetsemad tooted on kallimad ka riikide lõikes, misjuhul hinnapõhine elatustaseme võrdlus kajastab heaoluerinevusi hästi (sarnaseid eelistusi eeldades). Toidu puhul ei tundu, et hind kvaliteediühiku kohta riigiti sama on – näiteks troopilised puuviljad on troopikas nii odavamad kui ka värskemad kui nende eksporditurgudel.

Ostukorvierinevuste puudumise teine võimalik põhjus on, et riigis, kus antud toode hinna-kvaliteedi suhtelt halvem on, eelistavad inimesed seda toodet. Kui kasulikkusfunktsiooni erinevus tasakaalustab kvaliteedierinevuse, siis on tarbitav komplekt sama hindadeprofiiliga riikides sarnane. Esmapilgul tundub imelik, et parema tootega riigis huvitab see toode inimesi vähem ja täpselt kvaliteedierinevuse võrra. Seletus on harjumine antud toote keskmise kvaliteeditasemega oma elukohas: veini või juustu, mis eestlastele kõlbab, ei võtaks prantslased suu sissegi, samas head ja halba verivorsti või leiba pranslased eristada ei suudaks, aga eestlased valiksid peaaegu ühehäälselt hea.

Harjumust saab modelleerida näiteks nii, et inimese heaolu on kasvav funktsioon tarbitavatest kogustest ja suhtelistest kvaliteetidest (praegune kvaliteet miinus varem kogetud keskmine kvaliteet). Kui selline kasulikkusfunktsioon on inimestel sama, siis samade hindade korral tarbivad nad harjumuspärase kvaliteediga tooteid samas koguses. Varem kogetud kvaliteedid võivad inimeste vahel palju erineda, aga kui varasem kvaliteet võrdub praegusega, siis on ostukorv ühesuguse varandusliku ja hinnatasemega riikides sarnane. Harjumine võrdsustab heaolutaseme riikide vahel, neutraliseerides kvaliteedierinevused. Kui elatustasemega tahta mõõta heaolu, siis harjumise korral polegi tarbitav kvaliteet oluline, nii et selle eiramine elatustaseme võrdluses on õigustatud.

Odavamat toodet tarbitakse alguses rohkem, mis võib vähendada edasist heaolu sellest tootest, seega tarbimist. See tasakaalustab parema ja odavama kauba esialgset rohkem ostmist riikide võrdluses, muutes ostukorvid aja jooksul sarnasemaks. Taas muudab tasakaalustumine hinna- ja kvaliteedierinevused heaolu jaoks vähem oluliseks.

Äpp, mis ennustab kohaletulijate arvu

On palju veebilehti ja äppe, mis aitavad kohtumisi kokku leppida ja üritustele minekut koordineerida, näiteks meetup.com. Minu kogemuse põhjal umbes pooled internetis tulla lubajatest ei ilmu kohale, lisaks mõned tühistavad viimasel hetkel või hilinevad. See tekitab vahel ürituse korraldajale probleeme, näiteks kui ta on lubanud teatud arvu osalejaid organiseerida ja sellest sõltub kohaletulnute piletihind (grupisoodustus) või on minimaalne arv inimesi vajalik spordivõistkonna kokkusaamiseks. Lisaks sunnivad hilinejad ja teadmata kaduvad tulla lubajad teisi ootama, mis on tüütu.

Selleks, et motiveerida inimesi ausalt oma tulekuplaane teatama, lubadusi pidama ja õigeaegselt kohale tulema on vaja käitumisele vastavaid tasusid ja karistusi. Üks lahendus on, et osalejaks registreerujad peavad osalustasu ette maksma ja mitteilmumise korral seda tagasi ei saa. Tasuta või odavate ürituste puhul sellest ei piisa.

Hilinemise vältimise motiiv tekiks ka siis, kui on üldteada, et hilinejaid ei oodata, vaid transport väljasõidule läheb minuti pealt õigel ajal. Enamik inimesi ei taha aga hilinejaid maha jätta ja nii venib ooteaeg tihti pool tundi või rohkemgi, kusjuures paljude ootajate heaolukaotus kokku on tõenäoliselt suurem kui hilinejate võit mittemahajäämisest. Paljude ürituste kuulutusel kirjutatakse, et väljasõiduaeg on punktipealt täpne, aga seda lubadust murtakse peaaegu alati – ma pole veel kogenud üritust, kus keegi maha jäeti, et õigel ajal lahkuda.

Õige motivatsiooni tekitamiseks peaks hilineja või mitteilmuja maksma teistele piisavat kompensatsiooni, aga sotsiaalse sündmuse kontekstis on sellist nõuet keeruline jõustada. Mitteilmujalt on raske midagi sisse nõuda ja ka hilineja võib väita, et tal hetkel raha kaasas pole. Kui tahta trahvi teha vastavalt hilinetud minutite ja ootama sunnitud osalejate arvule, siis läheb ka arvutus enamiku inimeste jaoks keeruliseks. Lahenduseks on äpp, mis tuvastab telefoni asukoha põhjal, kes on kokkusaamiskohas õigel ajal ja kes mitte. Kohaletuleku registreerimiseks võib kasutada ka telefonide omavahelist lähisuhtlust (bluetooth, NFC). Äpp saab automaatselt välja arvutada hilinejate ja mitteilmujate kompensatsiooni ootajatele, selle äpiga seotud pangakontolt või krediitkaardilt maha võtta ja ootajatele kanda. Kes ei nõustu selliste tingimustega, võib kasutada muid ürituste koordineerimise vahendeid. Mittenõustumine signaliseerib ka teatud määral, et inimene ei plaani lubadusi pidada.

Sõltumata sellest, kas äpi kaudu nõuda mitteilmujate kompensatsiooni kohaletulijatele või mitte, on äpil veel see hea külg, et andmed inimeste varasemate registreerumiste ja asukoha kohta lasevad ennustada, kes lubajatest ilmub ja millise hilinemisega. Seega äpp saab automaatselt arvutada kohaletulijate arvu tõenäosusjaotuse, mis on korraldajale abiks planeerimisel. Samuti saab kroonilised mitteilmujad tulevastelt üritustelt välja jätta, näiteks neile mitte teavitusi saata – ka selle saab äpp automatiseerida.

Väga piiratud ulatuses on sarnane funktsionaalsus praegustel kokkusaamisveebilehtedel olemas, näiteks meetup.comi grupiadministraatorid saavad registreerida mitteilmujad ja programmeerida reegli, et kolm mitteilmumist eemaldab inimese grupist. Vajadus mitteilmujad käsitsi registreerida on praeguste äppide üks piirang. Ka ei erista praegused veebilehed tulekulubaduse tühistamise aega (viimasel minutil registreerumise tühistamine on sarnane mitteilmumisele) ega hilinemise kestust. Hea oleks ka arvestada lisaks inimese mitteilmumiste arvule tema õigeaegsete kohaletulekute arvu, mis aitaks paremini ennustada ta tulevast osalemistõenäosust.

Seasonings may reduce the variety of diet

Animals may evolve a preference for a varied diet in order to get the many nutrients they need. A test of this on mice would be whether their preference for different grains is negatively autocorrelated, i.e. they are less likely to choose a food if they have eaten more of it recently.

Variety is perceived mainly through taste, so the mechanism via which the preference for a varied diet probably operates is that consuming a substance repeatedly makes its taste less pleasant for the next meal. Spices and other flavourings can make the same food seem different, so may interfere with variety-seeking, essentially by deceiving the taste. A test of this on mice would flavour the same grain differently and check whether this attenuates the negative autocorrelation of consumption, both when other grains are available and when not.

If seasonings reduce variety-seeking, then access to spices may lead people to consume a more monotonous diet, which may be less healthy. A test of this hypothesis is whether increased access to flavourings leads to more obesity, especially among those constrained to eat similar foods over time. The constraint may be poverty (only a few cheap foods are affordable) or physical access (living in a remote, unpopulated area).

A preference for variety explains why monotonous diets, such as Atkins, may help lose weight: eating similar food repeatedly gets boring, so the dieter eats less.

Adapting to a low-salt diet is quick

Overconsumption of salt is a significant public health problem. People are reluctant to reduce the saltiness of their food, because it would taste bland. Eventually, preferences adjust so that a diet without added salt tastes normal and salted foods are perceived as too salty. The only question is how quickly tastes adapt.

My experience of stopping adding any salt to my food was that the bland taste lasted less than 3 days, after which I had fully adjusted to the new reduced level of saltiness. An easier way to adapt may be to gradually reduce the amount of added salt, as opposed to suddenly cutting off all of it, as I did. In that case, there may be no perceived taste difference, especially if the reduced salt is accompanied with increased amounts of other seasoning, like pepper. Given the smallness of the adjustment cost and the health benefit of cutting salt consumption, doing it is a clear and easy win.

Distinguishing discrimination in admissions from the opposite discrimination in grading

There are at least two potential explanations for why students from group A get a statistically significantly higher average grade in the same course than those from group B. The first is discrimination against A in admissions: if members of A face a stricter ability cutoff to be accepted at the institution, then conditional on being accepted, they have higher average ability. One form of a stricter ability cutoff is requiring a higher score from members of A, provided admissions test scores are positively correlated with ability.

The second explanation is discrimination in favour of group A in grading: students from A are given better grades for the same work. To distinguish this from admissions discrimination against A, one way is to compare the relative grades of groups A and B across courses. If the difference in average grades is due to ability, then it should be quite stable across courses, compared to a difference coming from grading standards, which varies with each grader’s bias for A.

Of course, there is no clear line how much the relative grades of group A vary across courses under grading discrimination, as opposed to admissions bias. Only statistical conclusions can be drawn about the relative importance of the two opposing mechanisms driving the grade difference. The distinction is more difficult to make when there is a „cartel” in grading discrimination, so that all graders try to boost group A by the same amount, i.e. to minimise the variance in the advantage given to A. Conscious avoidance of detection could be one reason to reduce the dispersion in the relative grade improvement of A.

Another complication when trying to distinguish the causes of the grade difference is that ability may affect performance differentially across courses. An extreme case is if the same trait improves outcomes in one course, but worsens them in another, for example lateral thinking is beneficial in a creative course, but may harm performance when the main requirement is to follow rules and procedures. To better distinguish the types of discrimination, the variation in the group difference in average grades should be compared across similar courses. The ability-based explanation results in more similar grade differences between more closely related courses. Again, if graders in similar courses vary less in their bias than graders in unrelated fields, then distinguishing the types of discrimination is more difficult.

Sõltuvust tekitava kauba koordinatsioonimäng

Teatud määral on ebatervisliku toidu, sigarettide ja alkoholi ostmine ja müük koordinatsioonimäng tarbijate ja pakkujate vahel. Kui ostjad on harjunud seda tervistkahjustavat kraami tarbima, siis on müüjal kasulik see nähtavale kohale paigutada (kassade juurde näiteks), et kiusatust tekitada ja müüki suurendada. Sõltuvus tähendab tagasisideahelat: kui tarbija seda kraami tihti ostab, siis tema harjumus süveneb. Tagasiside toimub ka inimeste vahel, sest sõprade tarbimine suurendab enda tarbimist. Uued inimesed saavad tarbijateks eelnevate ostjate eeskujul.

Teisest küljest, kui inimesed poleks harjunud ebatervislikku toitu ostma ja neid alguses reklaami ja tasuta pakkumisega ei meelitataks, siis enamik neist ei ostaks. Sel juhul poleks mõtet näkse ja sigarette poes nähtavale kohale paigutada – kui nagunii ei osteta, siis on kasulikum nähtav koht mõne paremini müüva kaubaga täita. Kui tervistkahjustav kraam pole nähtaval, siis ostetakse ja harjutakse sellega vähem või üldse mitte. Seega tarbijad ja müüjad saaksid koordineerida ühiskonna jaoks parema tasakaalu mängimisele, leppides kokku, et kiusatust tekitav ebatervislik kaup asendatakse väljapanekutes millegi muuga. Kes tahab seda osta, peab eraldi küsima. Selleks, et müüjatel ei tekiks kiusatust kahjulikku kaupa alguses reklaamida ja poes pilkupüüdvalt välja panna, peavad tarbijad hakkama vältima poode, kus tervistkahjustav kaup nähtaval on (ehk motiveerima müüjaid korratava mängu karistusega).

Pakkujad saavad samuti korratava mängu karistusega takistada ostjaid teatud kaupa küsimast, näiteks kui nõudlus piisavalt suureks läheb, siis alustavad selle laialdase reklaamiga. Kui ostjad oma tulevikust hoolivad ja sõltuvusse langeda ei soovi, siis piiravad nad oma nõudlust, et mitte reklaamikampaaniat ja kiusatusetekitamist valla päästa.

Equilibrium response to reduced material use for plastic bags

Probably to save material on the manufacture of the free plastic shopping bags in the US, these bags are small and thin compared to the ones in Estonia (which used to be free, but are now priced at significantly above production cost due to EU regulations on disposable plastic products). The equilibrium response of cashiers and customers to thin flimsy bags is to double-bag groceries, a practice unheard of in Estonia. After all, if one bag is sturdy enough, almost nobody will use two inside each other. I have successfully carried 10 kg in an Estonian plastic bag.

The equilibrium response to small bags is to distribute the groceries among many bags, especially the heavy or bulky items, for example to put each milk canister or large salad sack into a separate bag. Both double-bagging and the one-item-per-bag distribution lead to more bags being used in response to manufacturing each bag out of less material. It is an empirical question whether thinner, smaller bags result in less or more plastic waste overall. To incentivise reducing the one-time use of plastic bags and to encourage reuse, customers should have to pay for these, like in the EU.

One form of plastic bag reuse is as garbage bags (although it is only a one-time reuse, it is better than nothing). However, the flimsy free bags in the US come in bulk packs with the bottoms of the bags stuck together, so separating one from the stack often results in holes in its bottom an inch wide or more. The holes discourage many forms of reuse, including as trash bags, because small items (dust, crumbs, scraps) fall out. Partly the holes are due to the flimsiness of the material, partly to the way the bags are glued together to make a bulk pack.

Claims that tickets are running out

Both for paid and free events, the organisers often advertise that only a few tickets or places remain. The ad sometimes explicitly tells the viewer to register or buy now. Such advertising is costly, so there should be a benefit to the organiser. If the tickets have already sold out, then the benefit is zero, or at least smaller than if the event is not fully booked. The positive benefit from advertising a sold-out event is to build reputation for the future as an organiser of popular events, similarly to real estate agents putting a „Sold” sign in front of a house on which they closed the deal.

Given that the benefit of costly advertising is smaller when no tickets remain, some sellers should decide to advertise if and only if the event has not sold out. More generally, the probability of advertising should increase in the number of tickets remaining. In this case, rational buyers should treat advertisements saying that limited spaces remain as signals of the opposite – frequent ads show a desperate seller facing low demand. If most buyers think this way, then such advertising is counterproductive, because buyers want to delay their purchases when the probability of being able to buy in the future is large enough. The option value of waiting comes from the possibility that the buyer’s preferences change – a better event may become available, or some emergency may prevent the buyer from attending. Getting a refund for a ticket already bought is at least a hassle and may even be impossible.

The widespread claims of limited space remaining suggest that these ads boost purchases. One reason may be buyer attention – ads make them notice the opportunity to buy, which some of them wish to take advantage of. However, any ads draw attention to the event, so raising awareness cannot be the reason for the specific claim that tickets are running out.

For most events, buyers do not want to coordinate with the largest possible crowd, only with their friends, so do not prefer a fully booked event to a half-full one. Thus claims that the event is almost sold out are difficult to explain by the seller trying to coordinate buyer actions.

Some irrationality of buyers or the seller seems necessary to explain messages that demand is low. Either the buyers take the claim literally instead of using Bayes’ rule to infer the opposite, or the seller advertises despite ads decreasing demand.

It is an empirical question whether the target audience of ads saying that space is running out interprets these as signalling high or low demand, and whether these messages make people delay their purchase or speed it up.