McDermott and Shleifer double-team Taleb and Kahneman

Not really. But I still enjoyed reading the following passage from Andrei Shleifer's review of Daniel Kahneman's (superb) Thinking, Fast and Slow:

The fourth assumption of Prospect Theory is quite important. [i.e. In assessing lotteries, individuals convert objective probabilities into decision weights that overweight low probability events and underweight high probability ones.] The evidence used to justify this assumption is the excessive weights people attach to highly unlikely but extreme events: they pay too much for lottery tickets, overpay for flight insurance at  the airport, or fret about accidents at nuclear power plants. Kahneman and Tversky use probability weighting heavily in their paper, adding several functional form assumptions (subcertainty, subadditivity) to explain various forms of the Allais paradox. In the book, Kahneman does not talk about these extra, assumptions, but without them Prospect Theory explains less.  

To me, the stable probability weighting function is problematic. Take low probability events. Some of the time, as in the cases of plane crashes or jackpot winnings, people put excessive weight on them, a phenomenon incorporated into Prospect Theory that Kahneman connects to the availability heuristic. Other times, as when investors buy AAA-rated mortgage-backed securities, they neglect low probability events, a phenomenon sometimes described as black swans (Taleb 2007). Whether we are in the probability weighting or the black swan world depends on the context: whether or not people recall and are focused on the low probability outcome. [Emphasis mine.]

This exactly the issue I was trying to point out here. Sometimes people greatly overweight the risks of low probability events (as suggested by Kaheman and Prospect Theory)... other times they completely underestimate them (as suggested by Taleb's black swan metaphor). As a result, we should be cautious in trying to make generalisable statements about human behaviour from either one of these theories alone.

You may also recall that -- for my temerity in pointing out this apparent tension between Kahneman and Taleb's theories -- I was labelled an "idiot" by none other than Taleb himself. As I coyly suggested in that second post, Taleb's affinity for labelling others as idiotic meant that I was at least likely to be in good company. I am sure of that now having read Shleifer's article.

Why economists love auctions

Some background first: South Africa's power market is utterly dominated by (a) coal and (b) Eskom, the parasitical parastatal monopoly. In a bid to encourage both fuel diversification and competition, the government has determined that 3,725 MW of new capacity up until 2030 should consist of renewable sources operated by independent power producers (IPPs). This translates to roughly 10,000 GWh of actual future electricity generation.

Ignoring the fact that this is small potatoes in the scheme of things -- less than 5% of the country's current 240 TWh annual electricity consumption -- the point that I want to make here is mostly about how those IPPs are chosen.

Having played with various schemes, authorities eventually settled on something called the Renewable Energy Independent Power Producer Procurement Programme (REIPPPP). This is effectively a competitive bidding process, whereby applicants submit a guaranteed price that they are willing to accept for electricity that they generate in the future. In other words, it looks a lot like the idealised auction market advocated in economic textbooks.

So how have things turned out? Well, the results from the third round of bidding have just come in. (The previous bidding rounds were held in 2011 and 2012, respectively.) It would appear that things are progressing rather well:

The six successful solar PV bidders, which shared an allocation of 435 MW, were particularly aggressive with their pricing. Fully indexed prices using April 2011 as the base year showed that the average solar PV price fell from R2.75/kWh in bid-window one to 88c/kWh in the third round.

[...]Similarly, the price of onshore wind fell from R1.14/kWh in round one to 89c/kWh in round two and to only 66c/kWh in the latest round. A total of 787 MW was allocated across the seven wind projects

[...]Prices for the two 100-MW-apiece CSP [concentrated solar power] projects declined from R2.68/kWh in the first window to R1.46/kWh. 

We must of course be careful not to draw too many conclusions from the above figures. For one thing, the average price that South Africans currently pay for electricity remains lower than any of the above bids. Although, it is scheduled to approach (and even exceed, in the case of wind) them in coming years:

Even then, just because a small portion of wind or solar energy is expected to "reach grid parity" within the next five years, doesn't mean that the game is up for fossil fuels. There are major problems with peak balancing, intermittency and load-following constraints that renewables need to overcome, which I and many others have discussed at length before.

However, a 68% drop in the bid price of solar PV since 2011 -- say nothing of wind and CSP bids falling by nearly 45% -- is clearly impressive. Many people will see this as a evidence of how quickly renewable technologies are progressing. I wouldn't dispute that, but I also see it as a vindication of the auction system that was used for determining the winning bids.

It is something that South Africa's electricity sector could use a lot more of.

Bad science: Paleo diet edition

A while ago, I wrote a post praising the scientific approach that advocates of the paleo diet appeared to be adopting in arguing their case. In particular, the language used by people like Gary Taubes in discussing dietary health seemed to show a keen appreciation for the key principles underpinning the scientific method. This includes separating causation from correlation, controlling for placebo effects and selection bias, etc, etc.

However, apparently not all paleo advocates are such sticklers for good scientific practice. For example, see this blog post by Jacques Rousseau, which skewers a new "occasional study" by Tim Noakes.[*] There is a lengthy follow-up post that also well worth reading when you have time.

The short version is that Noakes is a very prominent sports scientist in South Africa. He also happens to be an extremely vocal proponent of the low-carbohydrate-high-fat (LCHF) paleo diet, having undergone a Damascene conversion in recent years. The occasional study in question was published in the South African Medical Journal and details 127 unsolicited responses that Noakes received from people who have followed his advice in switching over to LCHF. These correspondences tell of all manner of dietary miracles and health wonders that have followed as a result, from substantial weight loss to curing "incurable" diseases like type II diabetes.

The problem with this study should be all-to-obvious to anyone who understands anything about scientific practice -- more on that in a minute.  Furthermore, a lot of people are (rightly) up in arms about how it managed to get through the peer-review process and into the country's flagship medical journal. Cynical observers have not been shy in suggesting that this is almost entirely down to Noakes' status within the local research community and very little to do with the scientific merit of the study itself. (To be fair, I'm not sure that a double blind submission would have been possible in this case.)

Now, Jacques does a very good job in explaining the manifold problems of the study. He also points out that Noakes' position on the necessity of such anecdotal evidence is very inconsistent. (If we had proper, scientifically validated evidence about the benefits of LCHF then we wouldn't require anecdotal evidence on top of that. To argue otherwise is to suggest that the scientific evidence in favour of LFHC is not actually particularly strong.) However, I think some of the commentators actually do a better job of pinpointing exactly why this study does not belong anywhere near a reputable scientific journal. For instance, "Chris" writes:

[...]You could prescribe or promote absolutely anything, and you would see some people benefit. The key point is that the sample you have is self selected from those who benefited enough that they felt the need to contact you. That is likely to be a small number of the total number of people who did indeed benefit. And we have no idea what proportion of the total number of people to have tried LCHF those people are. The fact that there are 127 people who've shown a benefit is evidence of one thing, and one thing only: those people's ability to write you an email. Can you tell me exactly what their dietary regimes were, down to the last macronutrient? Can you assure me that the change in their diet was not simply a catalyst for them to become more active, thus they expended more energy? Can you tell me that there were no other outside influences that could potentially act as a confounding variable? You can't, and you say so yourself in the article. Which begs the question of why did it get published? If we can't say anything other than these people got amazing results and said they were on LCHF then what exactly can we say?[...]

Emphasis mine. A follow-up contribution by another commentator (who was actually involved in one of the cases that Noakes cites) is equally worth reading here.

To underscore something that Jacques and many of his commentators try to make abundantly clear; criticism of this particular study does not amount to criticisms of LCHF in of itself. The outcry is entirely about sloppy scientific reasoning and misuse (absence?) of the scientific method. Proponents of LCHF and other paleo-style diets may well be correct in identifying the causes of our modern dietary ills. I personally know more than a few people who credit it with helping them to shed weight and improve their overall sense of well-being. On the other hand, I can say exactly the same thing about friends who have converted to veganism. (You see the problem with anecdotal evidence!)

To conclude, if paleo advocates want to maintain scientific credibility, they need to distance themselves from this type of research. At the very least, they should not try to defend it.
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[*] You may recall that I actually mentioned Prof. Noakes at the beginning of my previous post. Rousseau is a senior lecturer at the University of Cape Town, whom it should be said took me for an introductory philosophy and business ethics course during my undergrad.

TEDxBergen

I mentioned the other day that I acted as moderator for the recent TEDxBergen conference. Videos of the various talks have now been posted online, but here are two that I particularly enjoyed as a sample.

1) Mads Nordmo gave a talk on moral psychology, which challenges the traditional "transactional" view of behaviour -- as is favoured by a lot of economic theory.

Mads is actually doing a PhD with me -- albeit in the strategy department -- and also has a degree in clinical psychology. His opening remark about showing that "it wasn't just beginner's luck" was in reference to a quip that I made about him winning a 'Best lecturer' award from NHH bachelor students. (Link in Norwegian.)

He used various examples to underscore his points, including the growing popularity of CrossFit and the paleo diet.[*] For instance, a purely transactional view provides us with very little insight into why people pay such exorbitant sums of money to join CrossFit gyms. The exercises mostly require far less equipment than ordinary gyms and we could all do as many sit-ups and push-ups as we want at home (for free!). However, Mads argued that these "movements" actually constitute a quasi-religious experience -- much like we would encounter at a rock concert or sports match -- where the sense of communal spirit and exaltation actually enable participants to achieve some kind of transcendence.

In the Q&A afterwards (not shown), I suggested that economics would normally explain the high membership fees paid to crossfit gyms as a commitment device. Mads agreed that this too is an important psychological driver. However, there is at the least no reason to regard such phenomena as mutually exclusive. (Interestingly, he also said that psychology is moving closer to economics... not simply the other war around, as is often asserted in some heterodox circles.) Anyway, he is a smart and funny guy, and I think that both traits are evident in his talk. Check it out:




2) The Grammy-nominated violinist, Peter Sheppard Skærved talked about reinvention and finding new purposes for old tools. Peter is a fascinating person -- the Library of Congress has described him as a polymath -- and I thoroughly enjoyed chatting to him about a range of topics, from anthropology to haptic technology, over the course of the day. In this video, he not only makes a compelling case for preserving "museum pieces" by actively using them as much as possible, but also treats the audience to a range of music pieces from across the ages.

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[*] As someone who has a number of friends into (at least one of) CrossFit and the paleo diet, I freely admit that I am predisposed towards finding this discussion both amusing and enlightening.

Joe Romm's cognitive dissonance on renewables, nuclear and shale gas

I used to be an avid reader of Joe Romm's "Climate Progress" blog. However, my enthusiasm has waned dramatically over the years due to his selective presentation of facts and data, stark intolerance for any opposing ideas and dogmatic stance on nuclear power. (On the plus side, his blog remains an excellent repository for climate news and he can be great fun when mocking the likes of Christopher Monckton.)

Probably the biggest problem that I have with Romm, however, is that he appears to suffer from acute cognitive dissonance. For example, the overriding theme of his blog is one of impending climate doom, yet he regularly proclaims that renewables are already at grid parity, getting cheaper by the second and ready for mass deployment. So, problem solved surely? Frustratingly, this is a recurrent theme on many green blogs, where Cassandra complexes are hard to square with wildly overstated -- or misleading at best -- claims about current renewable energy performance.

Such cognitive dissonance is again on display in one of Romm's recent posts, entitled "Major Study Projects No Major Long-Term Benefit From Shale Gas Revolution". The study in question is by Huntington et al, (2013) and contains projections from a broad suite of integrated climate models. In addition to GHG emissions, the researchers looked at the wider economic impacts of shale gas and their conclusions are rather more nuanced than Romm's excitable headline would suggest. In short, the final projections depend on a complex set of model assumptions and variable interactions. This is evident from the following paragraph that Romm actually cites from the study (emphasis his):

…this trend towards reducing emissions becomes less pronounced as natural gas begins to displace nuclear and renewable energy that would have been used otherwise in new power plants under reference case conditions. Another contributor to the modest emissions impact is the somewhat higher economic growth that stimulates more emissions. Reinforcing this trend is the greater fuel and power consumption resulting from lower natural gas and electricity prices.

Does anyone else see the irony here? Romm is lauding a study which questions the climate credentials of shale gas... and yet that largely depends on whether cheap gas displaces nuclear power -- a technology that he maligns at every opportunity.

More importantly, to say that shale gas confers no long-term climate benefits (in of itself) is extremely misleading. It all depends on whether it is complemented by a carbon price, as anyone interested in this debate (at least that I am aware of) readily acknowledges. You get a sense of this from the very figure that Joe Romm chooses to include in his blog post:

Comparison of low shale scenario (light blue), high shale scenario (dark blue), and a scenario depicting a reference case combined with a carbon price (green). This reference case is in between the low and high shale scenarios, while the carbon price starts at $25/tonne in 2013 and increases at 5% each year. Source: Huntington et al. (2013).

The dramatic reduction in emissions due to a carbon price is clearly evident. However, the above figure is still not really comparing apples with apples, since the carbon price is not adapted to the high shale scenario. (It is applied to a reference scenario that is somewhere in between the high and low shale cases.) Luckily, the data that would allow us to make the correct comparison is available here. I have therefore reconstructed the above graph, this time adding a new column that specifically combines the high shale scenario with a carbon price.

Based on Figure 13 of Huntington et al. (2013). The figure now includes a fourth column (purple) where a high shale scenario is combined with a carbon price.

This updated graph makes perfectly clear that the shale revolution can be fully compatible with deep long-term emission reductions, as long as it is complemented by a carbon price. To his credit, Romm does mention this briefly in the article and has also commented on the issue previously. Yet, by continuing to disparage shale gas and pretend that its supporters ignore the need for a carbon price, he simply serves to further polarise the climate debate.

THOUGHT FOR THE DAY: Adapting to the threat of climate change will require a broad suite of interventions. Nobody should claim that the proliferation of shale gas is a sufficient development for de-carbonising the global economy. However, together with a carbon price and other technological breakthroughs, it will likely form a very necessary component.

PS - It probably goes without saying that the economy also benefits from cheap and abundant shale. Huntington et al. state as much in their report (p. 7):

Higher shale resources reduce the costs of natural gas development and expand opportunities throughout the economy. Relative to its path in the low-shale case, [real GDP] is higher in all models that track the economy’s aggregate output. The cumulative aggregation of these GDP gains over all years is significant standing at $1.1 trillion (2010 dollars).

Showing this in graphical form is a little trickier, since some of the models actually take economic growth as an exogenous assumption, or don't extend all the way until 2050. Nonetheless, here is a graph showing a selection of models that compare changes in real GDP up until 2035.

Manufactured controversy and the "hockey stick": A football analogy

Even if you're only vaguely aware of the climate change debate, then you will probably have heard of the "hockey stick". You know, this bad boy:

Source: Mann et al. (1999).

This famous depiction of global temperatures going back into time has generated a lot of controversy. It doesn't seem to matter much to sceptics that the initial hockey stick(s) -- i.e. those produced by Mann, Bradley and Hughes (1998, 1999) -- have since been replicated by multiple studies using different lines of evidence and computational procedures. No, we are invariably told that the hockey stick is a fraud and has been debunked by the likes of Steve McIntyre and Ross McKitrick.

The problem with these debates is that they are necessarily technical and involve concepts that are very unfamiliar to most people. Whenever I tried to explain things to my friends and family, I could see their eyes glazing over as soon as I mentioned the words "principal component analysis". So here is a sports analogy that captures the essence of what critics like McIntyre and McKitrick got wrong.

Obligatory comment on the 2013 Nobelists

Seeing as it is very de jour to comment on this sort of thing in the econ blogosphere, here is a quick personal take:

I know that this year's laureates have raised eyebrows -- not least of all because people think that Fama and Shiller are at complete odds with one another. This doesn't strike me as especially correct. (Hansen is really the odd one out in this triumvirate, but we'll get to him in a second). For starters, and as pointed out many times over the last two days, Fama was one of the first people to publish results that ran counter to EMH predictions. Mark Thoma is exactly right in pointing out the EMH remains a really useful benchmark/framework for thinking about markets in an empirical sense. I've used it a fair bit when looking at energy and commodity markets for my own research and also when asked to to advise/comment on market trends. 

Shiller has played less of a formal role for me personally, though his housing index and his "dividend returns" data have been extremely handy tools in the blogosphere. The former is better known, but the latter is especially useful when, say, debating your average goldbug. (E.g. When dividends are taken into account, U.S. stocks have enjoyed inflation-adjusted returns of +/-1,000% since 1974. Gold, on the other hand, has yielded a rather more modest 130% over the same time period...)

The 2013 Nobelist who has had the most relevance for me, however, is Lars Peter Hansen. I suspect that this is true for many people working in economic research today, simply because the tools that he bequeathed us are so widely used in modern empirical work. Alex Tabarrok has one of the best "layman" explanations of GMM that I've seen here. Guan Yang has a more wonkish (but still accessible to anyone who is familiar with basic econometrics) exposition here.

Predictable Nobel Prizes in the Economic Sciences?

The subject line is taken from an email sent around my department by one of the finance profs. Here's the email itself:

A curiosity: In the very first edition of their textbook Financial Theory and Corporate Policy (Addison-Wesley, 1979), the authors Thomas E. Copeland and J. Fred Weston dedicated the book to 15 named “pioneers in the development of the modern theory of finance”. Out of these 15 pioneers, eight have since been awarded the Nobel Prize (viz. Debreu (‘81), Modigliani (‘85), Miller (‘90), Markowitz (‘90), Sharpe (‘90), Merton (‘97), Scholes (‘97), and Fama (‘13)), one was already a Nobel laureate (Arrow (‘72)), and three are dead and thus not eligible (Lintner, Black, Hirshleifer). So what about the chances of the three remaining finance pioneers Michael Jensen, Richard Roll, and Stephen Ross? By the way, this year’s laureates Hansen, Shiller, and Fama (a well as the previous laureates Engle, Lucas, Arrow, and Samuelson) are all among the twelve elected Fellows of the American Finance Association, recognized as having made a distinguished contribution to the field of finance.

So I guess it's even money on Jensen, Roll and Ross then...

PS - Here's the evidence.

Quote of the Day - Privacy

"At a moment of austerity and with a general sense that our state's ability to guarantee prosperity for its citizens is in retreat, that same state is about to make the biggest advance ever in its security powers. In public, the state is shrinking; in private, it is shrinking until it gets just small enough to fit into our phones, our computers, our cars, our fridges, our bedrooms, our thoughts and intentions."

- Taken from a long, but very worthwhile (and disconcerting) article by John Lanchester.

Why a functioning electricity grid is crucial to economic development

... in two graphs:

THOUGHT FOR THE DAY: Decentralised power is a nice ideal -- and in some cases is the best option -- but it remains a poor alternative to the grid for the moment.

PS - I've previously written about why the electricity grid is best viewed as a (regulated) natural monopoly here.