Saturday, September 4, 2010

Nerdy thoughts from the Congo.

Taxis in Bukavu

There are a lot of taxicabs on Bukavu's main road ("Avenue President Mobutu" on Google Maps for the interested people); that is, normal-looking cars (see picture) that stop if you raise your hand. They also use their horns excessively and often stop if you don't one, so it's easy to get a taxi. Cost is 400 Congolese francs (around 0.45$) and because they only drive the main road (because that road is paved) the only thing you have to do is to choose the correct side of the road, sit down and wait until you want to get out again.

An average taxi.

Once in these taxi cabs you will observe clearly different behavior among it's drivers. In brief, the drivers can be divided into two groups: 1. One group of taxi-drivers that drive fast, 2. One group of taxi-drivers that drive slow. Why? Why are there seemingly two different strategies to obtain the same goal: earn the most amount of money. When driving fast one covers more meters per fixed amount of time and thus opens up seats faster. But when driving slower it is less likely that you miss potential customers. What makes a taxi-driver choose for either of these strategies? Some possible determinants:
  • The other taxi drivers. Let's say that the taxi-driver knows from experience that there are more fast drivers than slow ones. As a result, the best strategy could be to become a slow driver because many potential customers are not picked up by the fast ones. So it could be that the distribution of fast and slow drivers is important.
  • The mood of the driver that day. Maybe there is nothing rational to all this. Maybe after a fight with his wife in the morning, the taxi-driver is angry and thus puts the metal to the gas a bit more than otherwise. Thus, maybe a taxi-driver doesn't choose either one strategy for the rest of his/her taxi-driving career. One step further, maybe what is actually happening is that a driver has some mixed strategy where he drives fast some days (or hours) and slow the other.
  • Reaction speed of the driver. If a taxi-driver is quick to react, he is less likely to miss potential customers. Consequently, these guys are maybe more willing to become fast drivers.
  • Volume of the horn. Maybe what is important is the volume of the horn. If it is possible from a long distance away to notify potential customers that you are coming they have more time to walk to the road, and it is thus less likely you will miss them; i.e. you are more likely to be a fast driver.
  • Any more?
Anyhow, I would love to know more about this, talk with the taxi-drivers while being with them in the car, etc. Unfortunately, these months Raul and I fall under IRC's security umbrella and there is a clear and strict rule that says "You are not allowed to use taxis in Bukavu". Aargh!

Phone credit in the Congo

As you know phones are important and very popular in Africa - also among the poor. If you do not have at least two phones you are not a real man.
There are several cellphone providers in Congo and Zain, Vodacom and CCT are the biggest. I have both Zain and Vodacom because they have the best coverage. I
n order to charge one's cellphone you buy phone credit. For example with Zain you buy "unites" (see picture below) of 500 (5$) or 100 (1$), type in *525* plus the 13 digit number and end with a "#".

500 Unites from Zain.

Now please follow me through the following steps:
  1. These cards seem to be valid for a year.
  2. Let's say there are a total of 1 million Zain users in Congo.
    [the DRC has a population of around 60 million people. Most of the country doesn't have coverage, but the big cities do. While Bukavu has only about 300,000 inhabitants, other cities are substantially bigger. The capital Kinshasa, for example, has 10 million inhabitants. So, let's run with 1 million Zain users for now.]
  3. Every week I use about 6 of these 500 unites pieces of paper; or 30 of them if would buy the 100 unites. While I don't call much, I am a Mzungu and very rich so let's say on average people use 10 of these pieces of paper per week. That is, per year at least 520,000,000 times (1,000,000 * 10 * 52) those 13 digits numbers are used.
  4. It's possible that Zain doesn't introduce these unites on the market at the beginning of the year, but gradually throughout the year. Also, we have to take into account that once a person uses one of these 13 digit numbers it can't be used anymore. However, we also have to take into account that there should be many more than the 0.52 billion pieces of paper around because sellers needs reserves.
  5. So, let's say that around half a billion of these 13 digit numbers work and we know that there are 10 trillion (10^13 possibilities).
  6. You see where I am going?
  7. 1 out of every 2,000 tries should give you a hit. That is, on average every 2,000 times you enter a 13 digit number you earn yourself a dollar.
  8. Many people in the Congo have cellphones. Many people are also unemployed. Filling in a 13 digit number takes less than 10 seconds, so every hour you can try around 400 times. In other words, when working an 10 hour day you earn yourself 2 dollars.
  9. IDEA: What about hiring 100s of people, giving them a list with 1000s of unique 13 digit numbers on it and they can keep 100% of the profit.
  10. BUT: I'm sure Zain must have thought and calculated this through; it would have been relatively easy for them to put 14 numbers on the cards instead of 13. I am still curious though.

Object #3.

Warm showers are dear to me and it is definitely one of the things I miss a lot when here (next to family, friends and great Dutch food); for proof of me missing showers see some previous posts here and
here. Earlier this week after coming back from Buja, Raul walked through the garden and saw the big watertank given in the picture below. After some more investigation he also saw a boiler stuck to the house. After having a mechanic passing by to get things working we had a working shower!

Watertank - placed higher than the house.


Now there are two problems (I am Dutch so I have to complain - our national hobby by lack of major other problems): First, my shower is too low: if I stand up my shoulder hits the shower-head. Secondly, and more profound, how are we going to do this? I live with three more people: Vera, Jenny and Raul. We all like showers (the longer the better). However, the watertank has a limited amount of water in it and is filled only every so many weeks. We can't monitor each other's shower consumption (I think Vera and Jenny wouldn't allow us to monitor them while they take a shower) and thus even if we make a schedule saying, for example, that each day each person is allowed a 4 minute shower, I'll be afraid they'll cheat; that they will shower for longer and thus use more water. Knowing that this is my future water, I thus prefer to use my future water now, so I'll be standing under the shower for longer as well. Vera, Jenny and Raul will do the same.

Let's see how quick we'll be without water. Btw, I'm heading upstairs now to take a shower.

1 comment:

  1. Some ideas...

    Object 1 looks like a good evolutionary game. You should be able to find an ESS that predicts the distribution of fast and slow taxis. You just have to figure out a convincing way of modeling the fitness of taxis.

    On object 3, you should figure out how many people can take a shower on a tank (let's assume 2). Then, everyday you randomly select 2 people to take warm showers. The catch is that you have to take your showers within a specified time (and you need to go first to prevent cheating), so you fix a time for the warm shower period.

    You might believe that on some days people really want a warm shower and other days they wouldn't mind if they could get one. Then you could make it so that if you want to be included in the lottery that day, you have to pay some fixed amount. The pool of money raised can be then split evenly among the 4 of you. Thus, people who put in money more frequently essentially pay those that do not put in as much.

    ...or you could just push Raul out of the way and take a one-hour shower