This marvellous book by Howard Wainer, Picturing the Uncertain World: How to Understand, Communicate and Control Uncertainty through Graphical Display, is an absolute must for anyone who claims to be involved in the search for empirical evidence. It's a sequel to the same author's Graphic Discovery and also in the tradition of Edward Tufte's The Visual Display of Quantitative Information. All applied economists should have read carefully all three books and keep them close by for reference. So should all other researchers – social science, medicine, education – anybody who needs to navigate the shoals of carrying out robust empirical work and communicating it to others.

Why do books which might seem to appeal only to the anorak tendency matter so much? They're not even about the underlying statistical analysis, only about presenting data graphically, after all.

The reason is that visual messages are much more powerful and effective than words or tables of figures. Yet so often data is presented graphically in either obscure or actively misleading ways. Figuring out the best and most accurate visual presentation is a good test of the researcher's statistical understanding and results. It will also get the message across powerfully. As both Wainer, in this book and his previous one, and Tufte point out in their many examples, most graphs whether in the media or academic papers are at best inadequate and at worst dangerously wrong. Conventional graphs swallow information, present it confusingly, and much software limits the kind of graphs that can be drawn in unhelpful ways. (Tufte is a well-known and vocal critic of Powerpoint graphs.)

Even though Wainer's book is mainly about graphical presentation, I derived some new insights about statistics from it too. One is his explanation of the dangers of false inference from grouping data into categories, say 'tall' and 'short' as related to 'clever' and 'stupid'. Depending on the boundaries chosen between categories, uncorrelated variables can appear to have any correlation you like: “Whenever we have two uncorrelated variables, we can always make the data do what we want so long as the sample is large enough.” (p153)

A second is the smallness of the tails of the normal distribution. If drawn correctly, a normal curve which is 1mm high 13 standard deviations away from the middle, as one might casually draw it if asked to go that far out, should be 3.5 times the size of the universe. (p171) With data for which the normal distribution is appropriate, such as the distribution of human heights, we're not interested in 13 standard deviations out. But the calculation is a stark reminder of the inappropriateness of the normal distribution for other data, the Black Swan world.

I should add that these are the most technical parts of the book – there are next to no equations and anybody should be able to follow the reasoning with a modest amount of concentration. It's also a rather beautiful book – lots of pictures, after all.

I'd certainly put it on students' required reading lists. Even econometrics courses do a poor job of teaching students about the importance of presenting their results, both to communicate them and to test them. It wasn't until I started my first job that I was taught to do a simple line graph of every data series I used to eyeball them for outliers, data errors and main statistical properties (stationary or not? obviously correlated with each other?).

Another reason Wainer's book and the others I refer to is so important is the much greater availability and use of graphics in the broadband web world. There is a lot of innovation in this field, and new software around. Hans Rosling's Gapminder has become well known through his TED talk. The OECD has introduced something similar on its website. There is much interest in mapping – here is an example that I found courtesy of a Tweet by @ChristianKreutz yesterday. With all this new technological capability around, let's encourage people to use it responsibly!

I neglected to review this great book about the luminaries of Enlightenment science and literature when I read it. Dava Sobel has just published a glowing review of it. She says:

The author describes his text as “a relay race of scientific stories,”
that “tries to capture something of the inner life of science, its
impact on the heart as well as on the mind.” In this the book succeeds
with verve. I didn't just read The Age of Wonder; I escaped to it, riding happily with its heroes through a blaze of adventures and ideas.

The book demonstrates marvellously not only the absence of two distinct cultures, arts and science, at the time, but also the mutually stimulating embrace between scientific and literary ideas. And of course the fever of discovery in the UK made it the world's industrial leader – something I'll come on to in a forthcoming post about Joel Mokyr's forthcoming book, The Enlightened Economy.

There are many books about Africa, and I seem to have read a lot of them. Richard Dowden's Africa: Altered States, Ordinary Miracles is certainly amongst the best. It distills his experiences travelling widely in sub-Saharan Africa for nearly 40 years, interpreting what he has seen and learnt . (He is now Director of the Royal African Society in London.) Like other outstanding journalists, Dowden brings two particular characteristics: the extent of his conversations, based on the access that being a foreign journalist has made possible; and a perspective that is both engaged – because who could avoid making moral judgements in many of these circumstances – and also distant, a bird's eye view.

There are lots of things about this book that I liked. One was learning something new on every page. It's a great read, combining vivid reportage with intelligent analysis. Another was the author's refusal to generalize. Almost every chapter is about a specific country, or sub-national region, or ethnic group, or village. The stories are used to illustrate wider points, but no reader could emerge from this making bland generalizations. Any of the chapters makes a great, concise introduction to an individual country's history and political landscape.

However, there are two quite powerful generalizations that emerge, not from being chapter subjects, but from the way they crop up in every specific example throughout the book. One is the utterly corrosive and pervasive corruption. Like Martin Meredith in The State of Africa, Dowden thinks this has its origins in colonialism, in the expectation formed by colonial rule that the state steals from the people. Between two and fourteen times the amount paid to African countries in official aid has been sent overseas to private bank accounts in London and Switzerland, he suggests. (And here's another charge to lay at the door of the financial services industry, the bankers for whom all money is welcome, no matter what its provenance.) But unlike Meredith, he firmly blames current political leaders in Africa for betraying the hopes and promise of liberation with every bribe they take or profit they skim. In this he is in harmony with a growing chorus of critics of everyday politics in so many Africa countries – including, of course, Barack Obama.

A second theme which emerges unannounced is the damage being caused by the aid industry – and here too Dowden is adding his authoritative voice to other aid critics. This ranges from his critique of the way the agencies feed the image of helpless, starving Africa to ensure they can raise funds to pay themselves and ensure their activities continue (p7) to drawing attention to their perverse role in supporting those who committed the genocide in Rwanda in 1994 (p248). The aid debate is raging amongst economists; those who advocate more aid won't find in this book any testimony at all to the positive effects they claim for it. Quite the contrary, although Dowden did often manage to travel only as a hitch-hiker on an aid agency plane or vehicle.

My personal interest was caught by brief sections about the impact of mobiles. Somalia (p113-117) is one country singled out as being unexpectedly transformed, but mobile anecdotes crop up throughout.

For all his criticisms of politicians and aid agencies and western governments, for all the moments of despair about horrific conflicts or the impact of HIV/AIDS, this is also an optimistic book. Its final words are: “Africa is finding itself.” I believe – hope – that this is the case. The end of the Cold War, the advent of new communications technologies, some easing of access to US and EU markets for African exports, have all made some contribution, as indeed has Chinese investment. The next 40 years will be better than the past 40 years Dowden describes.

Paul Collier's last book but one, The Bottom Billion, is one of the more thoughtful books I've read on the complex of reasons for the lack of economic growth in so much of Africa. His latest, Wars, Guns and Votes: Democracy in Dangerous Places, focuses on conflict as the root cause. He has taken up the theme of the need for others – donors, world powers – to tackle conflict first, in a provocative essay in The Boston Review. The magazine has also published a number of responses, many supportive, others more critical. This debate is well worth a read.

In particular, another of my economist heroes, Bill Easterly, criticizes Collier's approach as essentially neo-colonialist – or actually, plain old-fashioned colonialist. The debate is well worth a read. After a bit of pondering, combined with having read Richard Dowden's Africa: Altered States, Ordinary Miracles  this past week (a review will follow on this blog), I've ended up on the Easterly side of the argument. The bit of his critique that swung it for me concerns Collier's statistical conclusions:

“The logical fallacy leads to the conclusion that the poorest
countries systematically fall behind everybody else in economic growth.
Of course they do! Collier selected countries that were on the bottom
at the end of a specific period, so naturally they would be
more likely to have had among the worst growth rates in the world over
the preceding period. This ex post selection bias makes the test of
poor-country divergence invalid. The correct test would be to see who
is poor at the beginning of the period and then see if they have worse
growth than richer countries in the following years. When the test is
run this way, there is no evidence that poor countries grow more slowly
than richer countries.”

I think this debate will run on, however, especially after President Obama's strong speech in Ghana.

It's rare for me to plug a book I haven't read, but how could I resist doing so for The Enlightened Economy by Joel Mokyr. In fact, it's not yet published – Yale University Press is bringing it out in September. It's billed as focussing on “the importance of ideological and institutional factors in the rapid development of the British economy during the years between the Glorious Revolution and the Crystal Palace Exhibition.” In what sounds like a characteristic approach by Mokyr, he discusses “what key players knew and believed, and how those beliefs affected their economic behaviour.” The book should be a perfect complement to Robert Allen's recent book on the British Industrial Revolution, emphasising relative factor endowments, which I reviewed here. We're lucky to have two important new texts on this subject within a few months of each other, and I'm sure that Mokyr's, like Allen's, will take forward our understanding. So I'm looking forward to reading it when it's out.