Random thoughts of an economist

Need some incense, sir?

Posted in Economics by kafuwong on January 10, 2017

Stepping out of Wong Tai Sin MTR station towards the Wong Tai Sin Temple, you will see a line of four persons trying to sell incense to tourists.  If you are like most tourists, you will walk pass them and go to the point of interest – the Temple.

Unlike most tourists, I was not in a hurry.  In my recent visit, I paused to observe how they did business.  Initially, I wanted to know how often they were successful selling incense and the characteristics of the sellers who were more able to persuade.  Yes, there was a person with only one hand.  I would assume that more people would buy from him.  Nonetheless, I did not stay long enough to see any successful sales.

Initially, I thought the four persons would compete against each other for business.  To my surprise, they did not circle the potential customers at the same time to compete for business.  Instead, they took turns.  They organized themselves in a line.  The one in the front would approach the passer-by.  After the attempt, success or not, he/she would move to the end of the line.

The business appeared organized.  The obvious advantage of such arrangement is to avoid vicious competition and potential conflicts among the salespersons. That all salespersons circling the potential customers at the same time to compete for business can be understood as an outcome of non-cooperation, an inferior outcome.  That all salespersons lining up to approach potential customers one by one can be understood as an outcome of cooperation, a superior outcome.

What caused the cooperation?  Economists have studied repeated games and found that cooperation (which yield better outcome) is more likely in “infinitely” repeated games.

Now, think about the several local dominant players in specific sectors.  Have you ever wonder why they appear cooperative?

Are you well educated enough?

Posted in Democracy, Economics, Information by kafuwong on November 5, 2016

Saw a line from the Economist about elections in democratic countries like the United States.  

We are not educated well enough to perform the necessary act of intelligently selecting our leaders.

When the election result is not to our liking, it is easy for us to BLAME THE OTHER voters that they are not educated well enough.  Wait a minute.  Is it so easy to be educated well enough?

Show me an orange and an apple. I can make a choice between the two. I can do so by look at their shape, size, color and smell.  That used to be a simple choice in the old days.  I might make a wrong selection occasionally but I will learn from my mistakes over time.  

But, nowadays, if it is known that most people chooses orange (or, are predicted to choose orange), the apple owner may decorate the apple so that it is more appealing to the consumers. By changing the shape, size, color and smell, say.  When most people now choose apple, the orange owner may decorate the orange so that it is more appealing to the consumers.

The competition can continue. More decoration techniques are invented to FOOL the consumers. The consumers are however ultimately interested in the taste of apples and orange. Fooled by the decoration, we as consumers may end up buying a bad apple.

To be a wise consumer, we need to understand the tricks of the decoration and thus be able to uncover the real thing.

And, that is not easy!  Certainly very costly!

My dear books, good bye.

Posted in Economics, Life, Uncategorized by kafuwong on July 21, 2016

As I prepared my departure from HKU, I started to sort out things that I wanted to take home, and what to discard.

As I did not have to pay for the usage of my office space, I had kept a lot things that I had rarely touched.

Now, leaving HKU means that the usage of space at home to keep these stuff will become costly.  Like most people living in Hong Kong, I cannot afford to keep everything I have accumulated during my 14 years at HKU.  

I asked myself repeatedly, “Is there anything I cannot live without?”  “Is there anything I will likely use in the near future?”   Most of the stuff in my office do not pass these tests.

Mostly books, I decided to give away.  There are a lot of books that have sat on my shelf for a long long time and had rarely been referred to.  Time to say good bye to them.

Now, in retrospect, I should give them out long long time ago.

A thought on how to evaluate whether education expansion helps improve mobility.

Posted in Econometrics, Economics, Hong Kong, Statistics/Econometrics, teaching by kafuwong on September 11, 2015

We often see reports comparing the median income of university graduates over time. The sad news is that the median income of university graduates are often found declining over time. One common conclusion is that the expansion of university education has not helped improve social mobility. And, university graduates seem to be doing worse than before.

While median income is easier to compute, I do not think it is the right measure to address the question of social mobility, or how university graduates nowadays fare when compared to the previous cohorts. A correct measure is some form of median income with an control of the expansion of university education.

Imagine the following hypothetical situations. Suppose that we have a stable population structure. Suppose 20 percent of high school graduates can attend university ten years ago. Imagine we end up with 20 persons achieving high school level and 5 persons achieving university level. The median income of high school graduates was X1 and that of university graduates is Y1. Y1 is usually higher than X1, reflecting the difference in ability of the two groups and added value of education.

For the sake of illustration below, let’s assume that the 5 university graduates have incomes of 12100, 12200, 12300, 12400, 12500. Obviously the median income is 12300. That is, Y1=12300. Let’s further assume that the top 5 earners of high school graduates earn 8100, 8200, 8300, 8400, and 8500 respectively.

Today, due to the expansion of higher education, 40 percent of high school graduates can attend university. Following from the example above, we end up with 15 persons achieving high school level and 10 persons achieving university level. Suppose then the 10 university graduates have incomes of 11100, 11200, 11300, 11400, 11500, 12100, 12200, 12300, 12400, 12500. Let’s denote the median income of high school graduates as X2 and that of university graduates as Y2. Note that the median income X2 is based on a smaller group size while that of Y2 is based on a larger group size. We can easily imagine that X2 will be lower than X1 because we can imagine that the top five earners (“more able”?) were removed from the original high school group and put into the university group. And Y2 will be lower than Y1 because the university group includes the “less able” ones.

Thus, if we compare the change of median income by education groups, we are bound to see a deterioration in income in BOTH GROUPS. Some would conclude that education expansion is bad.

Wait a minute. Obviously, the five persons who achieved university level because of the education expansion achieve a higher income. (11100, 11200, 11300, 11400, 11500) versus (8100 8200 8300 8400 8500). A substantial improvement in social mobility (as measured by income) due to the education expansion, isn’t it?

That is, we are evaluating whether education expansion is useful, we should focus on these 5 persons who had not the chance to study university but now have the chance to do so.

If we still insist on using measures similar to median income of the university graduates across time to conclude whether university graduates are doing worse than better, we need to make an adjustment. From the example above, we probably should compare the top 25 percentile income level today to the median income 10 years ago!

Repairmen needed to give electrical pencil sharpeners a second life

Posted in Economics, Environment, Hong Kong, Parenting by kafuwong on July 16, 2015

A year ago, the ten-year-old electric pencil sharpener in our office began to fail. It was one of those better electric pencil sharpeners and could stopped automatically on sharpened pencils. Our office had no choice but to dispose the old one and to buy a new one of the same model. I took the old one home to let my son play with it.

The new one malfunctioned within days. As it was under warranty, the office then got a replacement. The newly replaced one worked but lacked the function of automatically stopping on sharpened pencils. My colleagues called the company for a repair. The salesperson said the new one did not have this function of automatic stopping and refused to send anyone to repair it. (Bad salesmanship, and lies as well!) After a year, it failed. Now, as it was no longer under warranty, the office decided to discard it. Again, I took it home to let my son play with it.

Were we successful in resurrecting the two pencil sharpeners? To my colleague’s surprise, we did. (I said “we” because I made substantial contribution.) On the ten-year-old pencil sharpener, we discovered that it just needed some oil — it took us a long time to discover. After applying some oil, it worked like new.

One the one-year-old, the major problem was a mis-alignment of a switch. Not only that we brought it back to life successfully, we also fixed the function of automatically stopping on sharpened pencils.

No, I am not trying to brag about how good we are in repairing the machine.

Here is my observation: Many years ago (when I was younger), a lot of broken electrical appliances were repaired and used for a long period of time. Now, most broken electrical appliances are thrown away. The natural question is WHY!

I think the answer lies in the cost of purchasing new electrical appliances and the labor cost of repairment. The labor cost has gone up substantially in Hong Kong. The cost of buying new electrical appliances is low. When the cost of repairment is higher than the cost of buying new electrical appliances, the decision is not to repair. As more people make similar decisions of not to repair their broken electrical appliances, more broken electrical appliances will end up at landfills.

How to reduce the amount of broken electrical appliances in landfills? We need more rag-and-bone men and repairmen.

Anyone interested in joining me to collect and repair broken electrical pencil sharpeners?

Why were there no toilet papers in the public washrooms in the old days?

Posted in China, Economics, Parenting by kafuwong on May 8, 2015

Most readers are astonished: Most of the “wind chimes” hanging on trees for a “Wind Chimes Festival” in China were stolen by tourists/visitors!

Tourists should not have stolen the wind chimes, should they? It is not ethical to take the wind chimes that is not yours.

On the other hand, shouldn’t the officials organizing the festival have predicted the stealing to happen? Not many years ago, Hong Kong provided no toilet papers in the public washrooms. Simply because the whole roll of toilet papers would be taken away as soon as it was installed. Anticipating this outcome, the government officials decided not to supply toilet papers in public washrooms (or at least not to replenish).

Why would Hong Kong people not remove the whole roll of toilet paper from public washrooms nowadays? Hong Kong people has become more ethical? Was there a campaign to teach Hong Kong people to be more ethical, and not to remove the whole roll of toilet paper from public toilet?

Yes, it is possible that Hong Kong people have been educated to become more ethical. On that, I am not so sure. I think the more important reason is that Hong Kong people has become richer. A roll of toilet paper is nothing when compared to their income/wealth. That is, richer people tend not to steal things like the toilet paper. (They may steal things that are of bigger value relative to their income/wealth.)

Thus, if the “wind chimes” is cheap relative to the tourist income/wealth, we would expect the wind chimes to stay on trees for a while. If the “wind chimes” is expensive (say gold wind chimes) relative to the tourist income/wealth, we would expect the wind chimes on trees to be gone in no time.

The redemption rate of cake coupons

Posted in Economics, Hong Kong, Information, teaching by kafuwong on February 16, 2015

A friend was trying to redeem his cake coupon from a chain bakery. His coupon was two days from expiry. If he had not done it in time, the chain bakery will gain.

Hm… What is the redemption rate of cake coupons? That is, how much do the chain bakery gain per year due to people’s failure to redeem their coupons?

I do not have the numbers. Nonetheless, here is a thought experiment.

Imagine that 40% of the cake coupons are not redeemed. Shop A is willing to sell the coupons at 60% of the nominal value. Of course, shop A will try to sell the coupons at the nominal as much as it can. Selling at full nominal value will ensure a gain of 40 dollar gain per 100 value of coupon. This is good money.

The problem is that shop A is not alone. Likely, shop B also sells similar coupons. If shop A is selling at full nominal value, shop B can steal shop A’s customers by selling the coupons at a small discount, say 5%. If information is perfect, all customers will buy the coupons from B. But, A is not stupid. Seeing the loss of customers, it will try to steal shop A’s customers by selling the coupons at a bigger discount, say 10%. …. We can easily see that this competition game will continue until both shops will be selling near at 40% discount. We see the power of competition.

Now, how do we get an estimate of the redemption rate? Easy. We go to shop A, tell them that we are going to get marry and are planning to buy a lot of cake coupons, and ask them the discount we can get. Do the same to shop B, just to double check. That “1-discount” will be close to the redemption rate.

Does it look suspicious to you? Check please!

Posted in Economics, Information, Leisure, teaching by kafuwong on October 9, 2014

A friend sent me a striking table of “actuarial study of life span vs. age at retirement”. The table shows a person who retires at age 49.9 will die at 86 on average, and a person who retires at age 65.2 will live to 66.8 on average. The data suggests that I should consider retiring early.

Wait a minute! A person who retires at age 65.2 will live to 66.8 on average? It is absolutely not consistent with my casual observations.

I could not help doing a quick search of “actuarial study of life span vs. age at retirement” (without the quotation marks, of course). Surprisingly, I found that the table was founded based on a real study –- a Boeing study done almost 30 years ago. The study has been circulated in the internet for many years and finally reached me. Lucky me!

Interestingly, Boeing has tried to tell the public that the chart or table was wrong. According to Boeing, there is simply no correlation between age at retirement and life expectancy of Boeing retirees.

Why are such rumors still around? I think it is because most users in the internet are not willing to spend much time questioning and verifying the accuracy of the information. Spreading some seemingly striking news/information attracts attention. Most of us feel happier with more attention from our friends. There is a cost of verifying the accuracy of the information, though. Such comparison of COST and BENEFIT dictates our decision whether to spread the rumors, though implicitly.

Spreading news/information is understandably more costly to people with good reputation of providing accurate information. Thus, one would expect reputable reporters less likely to spread news/information without careful verification. That tells us where to turn if we want accurate information and where to turn if we want some rumors to enjoy.

I do not like this kind of rumors. I try not to spread suspicious items. At the same time, though, I do like to test my ability in catching such problematic information and verifying them. It has become one of my major pastime. LOL.

Additional readings:
http://www.boeing.com/companyoffices/empinfo/benefits/pension/seminars/Rumor.pdf
http://www.intmath.com/blog/retiring-early-means-a-longer-life-an-urban-myth/822
http://www.bbc.com/news/magazine-18952037

Are you sure what you saw was black?

Posted in Economics, Hong Kong, Information, teaching by kafuwong on October 6, 2014

Beside the extreme of white and black, there is a spectrum of grey. Given a color of grey, some might conclude it as black and some white.

It depends on the referenced color. When grey is put next to white, it looks like black. When grey is put next to black, it looks like white.

I feel that I saw black. Then, I am sure that what I saw was not white. Because, if the color were in fact white, I would not conclude black — even if the reference were white.

How can I know that the color I was is likely grey? The color was in fact grey if some of my friends and I saw black and many others saw white.

The views of others are so important! Their views provide important information for me to correct my view of black. Those who are willing to tell me their different views deserve my best respect. Thank you.

Who would rush to claim that he/she is one hundred percent sure what he/she saw was black? Those who do not know the existence of grey. Those who fail to deduce the color of grey from the conflicting views. If these two groups of people insist what they saw as the only truth, clashes may follow.

One solution is education! Education helps broaden our horizon (seeing the existence of grey) and train our critical thinking (concluding grey)!

[Fine print: Assume that all of us are telling the truth.]

A will for a will!

Posted in Economics by kafuwong on September 25, 2014

One of my best friends put the following in his Facebook status

I’m finally meeting with a lawyer to draw up a will. If you were thinking of doing something extra nice for me, now would be a good time.

I enjoyed so much reading how his friends replied. Of course, there is no point of summarizing their replies. But, I thought you might be interested in what I said to him.

Funny you, my friend! Seeing your status, I will be meeting with a lawyer to draw up a will very soon. If you were thinking of specifying some gift for me in your will, now would not be a bad time.