Category Archives: measurement

NBMR – still relevant

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With several life insurers reporting financial results, including horribly broken measures of new business profitability such as VNB margin or VNB / PVFNBP, it feels like time to roll out New Business Margin on Revenue again and describe why it is a much better measure.

It is a good time, but I don’t currently have the time. I’m going to try to prepare a basic spreadsheet example to make it clearer. I’ve also decided on a provisional treatment of pure financial instruments that I hope will give useful results.

Watch this space.

Dangerous information

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Land Restitution is an emotional issue.

It’s not really a practical issue since recent history has shown that not all beneficiaries of land restitution ultimately want to work the land. This is also entirely reasonable given the change of our economy from a primary economy to a secondary and tertiary economy over the last 50 years.

So when I read that the SA Institute of Race Relations states that more land could have been returned to black beneficiaries if money was not offered instead, I just wonder what the point is.

If people are accepting cash rather than land, it may well be because they want the cash rather than the land. Given land, I’m not aware that there is a prohibition on selling that land (which would be a poorer form of property right than they originally had so surely can’t be allowed) so we could end up in the same situation.

The danger for me is that the measures of land restitution could so easily, accurately and misleadingly, refer to the amount of land that has been restituted, or the amount of land currently in the hands of black South Africans, when this is clearly not an accurate measure of what progress has been achieved.

 

Lose a Million

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The Make a Million competition, as I’ve mentioned before, is an awful idea. It doesn’t promote investing or even “normal” trading, but rather massive, speculative risk-taking trading because the prize for performing well is nothing and the prize for performing best is significant.

I’m continually disappointed that Moneyweb continues to partner with this distraction.

As I’ve done in the past, I’ve analysed very quickly some of the results of the most recent competition. As background to that, the basic rules are:

  1. Put up R20,000 of your own money
  2. Trade over three months in currencies, commodities single stock futures and some index trackers.
  3. Whoever has the most at the end wins a million rand
  4. Everyone keeps what is left of their initial “investment”

So let’s be clear, there are no long-term investment learnings here.

The winner did return 165.5% over 3 months, which is not an impressive performance even though it might look like it.  The point is, given the volatility of the investment universe available for the competition and the encouragement towards rampant risk-taking, it’s entirely pedestrian performance.  It’s very likely an individual’s performance will be good given the wide range of possible outcomes.

Let’s look at some other statistics

Average performance -18.4%
Annualised average performance -73.4%
Proportion making a profit 26%
Total amount won -R1 020 762
Standard Deviation of performance 48.0%
Annualised standard deviation 96%

These are not performance statistics of which to be proud. They are similar to the losses incurred in prior competitions.

So in short, the competition cost the entrants in total just over a million rand. Losing a million rand is a great way to Make a Million.

SA population pyramids and brain drain

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The world’s population is now estimated to be 7 billion. That’s a big number, but with slowing growth rates (and negative population growth in several developed countries) the most headline grabbing stories of rapid overpopulation are nothing more than echoes of the same stories of the last few thousand years.

Some of the stories around in the news did prompt me to take a look at the South African population pyramids as estimated by Stats SA. Now these figures are extrapolations based on demographic models and the results of the 2001 national census.

As an actuary interested in economic policy I was disappointed with myself that I was surprised by the shape of these pyramids. Some striking messages to say the least.

population pyramid all

population pyramid all

The overall population pyramid is relatively typical of developing countries with a significant portion of the population under 15 and a significant majority under 35. The growth rate is clearly already slowing, but a surge of youth, many to poor families with limited prospects for good education is still working its way through our population ranks. Continue reading →

How not to calibrate a model

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Any model is a simplification of reality. If it isn’t, then it isn’t a model as rather is the reality.

A MODEL ISN’T REALITY

Any simplified model I can imagine will also therefore not match reality exactly. The closer the model gets to the real world in more scenarios, the better it is.

Not all model parameters are created equal

Part of the approach to getting a model to match reality as closely as possible is calibration. Models will typically have a range of parameters. Some will be well-established and can be set confidently without much debate. Others will have a range of reasonable or possible values based on empirical research or theory. Yet others will be relatively arbitrary or unobservable.

We don’t have to guess these values, even for the unobservable parameters. Through the process of calibration, the outputs of our model can be matched as closely as possible to actual historical values by changing the input parameters. The more certain we are of the parameters a priori the less we vary the parameters to calibrate the model. The parameters with most uncertainty are free to move as much as possible to fit the desired outputs.

During this process, the more structure or relationships that can be specified the better. The danger is that with relatively few data points (typically) and relatively many parameters (again typically) there will be multiple parameter sets that fit the data with possibly only very limited difference in “goodness of fit” for the results. The more information we add to the calibration process (additional raw data, more narrowly constrained parameters based on other research, tighter relationships between parameters) the more likely we are to derive a useful, sensible model that not only fits out calibration data well but also will be useful for predictions of the future or different decisions.

How not to calibrate a model

Scientific American has a naive article outlining “why economic models are always wrong”. I have two major problems with the story: Continue reading →

Greek default?

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So European politicians have more or less agreed a deal which may, more or less, push some of their problems to one side for a period. Yes, I’m not madly optimistic about this as a cure-all.  This is not the end of the Euro problems.

Part of the deal is a “50% loss for private investors”. Which is part true and part nonsense but will be an effective Greek default when enacted / agreed. (I don’t care how “voluntary” it may be, it’s a default and almost all definitions of default include restructuring of debt in any way that isn’t what was originally promised.)

Why is it only partly true? Well it’s not necessarily a “loss” for private investors. The probability of default on Greek bonds has been just about 100% for a while now. This probability of default is derived from market prices for Greek bonds and market spreads on Greek Credit Default Swaps (CDS) and an assumed Loss Given Default or Recovery Rate for investors when the bonds do default. Actual Recovery Rates vary widely, but often analysts plug in the average Recovery Rate over most of this century on unsecured debt which is around 40%.

So if market prices for Greek bonds assumed 100% default probability and a 40% recovery, then a 50% recovery doesn’t sound so bad. The potential downside is that Greece may still (need to) default on these written-down bonds at some point in the next two decades.

So the real question is what will the new probability of default be? Then we will know whether investors “took a loss” and perhaps gain the market’s view on how successful the deal really will be.

Narratives vs facts

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I don’t usually write about The Final Frontier, but this article has a great parallel to what I do write about.

It’s worth reading the entire article, but the main message is that we cannot use the dream or story or fairy tale of imminent migration into space and other planets as an excuse not to deal with the very real problems we have on Earth right now. The misconceptions, Hollywood induced and otherwise, about the ease of space travel or even the extent of our current capabilities, are massive.

As with so many things, the stories that fill our society can be very different from the harsh reality.