Autoriarhiiv: sanhei

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

Lisa kommentaar

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

Lisa kommentaar

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

Lisa kommentaar

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

Lisa kommentaar

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.

Free wifi lies

1 vastus

Many airports, hotels and other public places advertise free wifi, but in a significant fraction of them, the wifi does not work, e.g. in Doha Airport. One view about this is that you get what you pay for. On the other hand, the claim of providing free wifi makes people try to connect and wastes their time. Everyone would be slightly better off if the non-working wifi was not advertised – the advertiser would save the cost of printing the „Free wifi” signs and the visitors would save time.

It is cheap for the service provider to check whether the wifi is in fact working – just program a few cheap used smartphones to periodically try to connect to the wifi and send a notification to IT if the connection attempt fails. The connection failure may even trigger an automatic restart of the router.

Some airports may have wifi available, but only to a restricted group of people. For example, in India, connecting requires a local phone number, which most international travellers do not have. In Singapore and Shanghai airports, the wifi requires either a local number or scanning one’s passport in a kiosk, and the kiosks are sometimes out of order. Again, looking for the kiosk and trying to scan wastes time.

Intermittent wifi may be better or worse than none, depending on what fraction of time it is available and people’s average time cost of trying to connect.

Online check-in lies

Lisa kommentaar

Almost all airlines advertise the option to check in online and send email reminders to do so. In my experience, some airlines (Qantas, Air New Zealand and Qatar Airways) frequently do not allow online check-in despite falsely claiming that it is always available, or only unavailable to underage people and large groups. Email reminders to check in online seem like mockery in this case, but are still sent.

The false advertising of online check-in wastes customers’ time by encouraging them to start the data entry process. Often the process can be almost completed and only at the end does a message appear saying that online check-in is unavailable. To reduce the wasted time, the process should be stopped as soon as possible whenever it cannot be completed but is nonetheless started. It seems a simple IT fix to not send the automated reminder emails when online check-in is unavailable, and display the message „Online check-in unavailable” at the start of the data entry process instead of at the end.

A similarly ironic tone to falsely advertising online check-in is achieved by sending „we value your opinion” emails from a no-reply email address, or claiming to listen to customers but providing no contact email or phone on the website. Such mockery is practiced by many large companies. Sometimes the firms provide a feedback form that is user-unfriendly and requests lots of personal data. Or they may refer inquiries to a very limited FAQ section. The FAQ sometimes lists questions no real customer would ask, along the lines of „What makes your product so excellent?” These questions are in the FAQ just to let the company repeat their marketing slogans.

Chair material should be breathable

Lisa kommentaar

Strangely enough, fancy office chairs are often upholstered in leather or other non-breathable material. After an hour or so, sitting in them gets uncomfortable because the moisture does not evaporate from the skin that is separated from the chair only by some cloth. However, people usually sit in office chairs for hours at a time, and I doubt that the chairs are designed to deliberately provide some discomfort to encourage users to occasionally stand up for health reasons. Especially in a hot climate when the air conditioning may break down or just be too weak, a breathable chair would make much more sense. Making a mesh chair is simple: stretch a breathable fabric on the chair frame. The small holes in the fabric let moisture evaporate from the surface. A mesh chair is probably cheaper to manufacture than a leather-upholstered one.

A reason for using leather may be to signal wealth by using a material associated with expensiveness.

Modern synthetic meshes are as durable as leather for practical purposes, because sitting in a chair is not a high-wear use.

Mugs, pens and USB sticks as advertisements

Lisa kommentaar

Several universities I have visited give free mugs to seminar speakers as advertisements for themselves. Similar branded objects (pens, USB sticks, T-shirts, baseball caps) are handed out by firms and political campaigns as part of their marketing.

The idea of giving people practical objects instead of flyers, junk mail or banners is to make the recipients use these objects (as opposed to throwing these away or storing them at the back of a closet), preferably in a public setting, and thus increase the visibility of the advertiser. For this, the more usable the handout, the better.

Unfortunately, the people ordering these objects in bulk and paying for the brand logo to be printed on these are busy administrators who do not connect the overall purpose the marketing campaign to the properties of the objects. Specifically, the mugs should have a large handle that lets more than two fingers hold it, the mug should be short with a wide mouth for easy filling and washing, and should not be too fragile.

Pens should write well and be ergonomical, not angular or too narrow. I have seen branded pens violating all these suggestions. For example, the Australian National University pens are of flimsy plastic, create ink splotches and the ink runs out quickly.

The USB sticks handed out by the University of Queensland had a metal cover which increased the USB drive’s bulk and scratchiness. Also, the USB was wide and thick, making it impossible to plug in side by side with another USB. The small capacity of the USB was also behind the times.

To advertise with an object, it would make sense to print the advertiser’s name and other relevant information in large readable font on the object. The logo is not useful unless it is already widely known by the target audience and associated with the advertiser. The readability suggestion is violated by the Singapore Management University’s mug, which has SMU written on it in complicated calligraphic script that is difficult to decipher even for someone who knows what the abbreviation SMU means.

For people to develop a positive view of the advertiser, the object should not seem too cheap or bad quality. By contrast, most free T-shirts are the cheapest ones that could be bought wholesale, made of the most threadbare and transparent cotton, which discourages their use.

Slippery sidewalk paving

Lisa kommentaar

In Singapore, the streets are well planned and maintained, smooth and clean like everything else. However, the sidewalks have one illogical aspect: the pavement is smooth stone, which gets very slippery when wet. Singapore is tropical and humid, with frequent rain. When initially paving the sidewalks, it would be easy and probably cheaper to use rougher covering (asphalt for example) that would not get slippery in the rain. After the smooth pavement has been laid down, changing it is of course costly, and if the locals have adjusted to the slipperiness, then switching the sidewalk cover may not be worth it.

The University of Queensland has a similar problem with the sidewalk in front of its main building. The sidewalk is coarse, like yellow asphalt with 1 cm stones in it instead of sand. One would expect such a coarse surface to provide good grip in all conditions, but unfortunately the looks are deceiving. When that sidewalk gets wet, it becomes slippery like polished glass. Again, it would be cheaper and more practical to pave that sidewalk with asphalt.

A broader point generalising the above observations is that things should be field-tested in realistic conditions before putting them to widespread use. For example, the sidewalk stones should be walked and biked on under all local weather conditions before paving a street with them.

Perhaps the smooth stones in Singapore are meant to make street cleaning easier. Still, there are materials that do not become slippery when wet and are smooth enough for mechanised cleaning and cheap enough to use as pavement.