Thursday, October 17, 2019

Anyone Want a Talk in or Near Australia?

I am attending a conference in Sydney, Australia, from May 22nd to May 24th. I plan to spend about two weeks on the trip, so would be happy to give other talks in Australia or possibly places nearby — as viewed from the U.S. — such as New Zealand or Singapore. If you are interested in arranging such, let me know here or by email (ddfr@daviddfriedman.com) or both.

Anyone want a talk in or near Europe?

I am going to be in Madrid, March 6-8th, for the European Students for Liberty convention. I plan to spend about two weeks on the trip, so would be happy to give other talks before or after. If you would like to arrange one, get in touch either here, via email (ddfr@daviddfriedman.com), or both.

Saturday, July 06, 2019

It Feels So Good When You Stop

The stock market is also soaring, with the Dow Jones Industrial Average setting a new record high this week on optimism about an end to the U.S.-China trade war (News story)
I have a new explanation for Trump's trade war with China. It makes us poorer. Ending it will make us richer, raise the stock market, make Trump less unpopular with tech firms. Voters vote largely on current information. So if he ends it a few months before the election ...

Which reminds me of the story of the man in the insane asylum for hitting himself in the head with a hammer. When one of the doctors asked him why he did it, the answer was "Because it feels so good when I stop."

Andre Norton on C.J. Cherryh

I recently started rereading Gate if Ivrel, C.J. Cherryh’s first novel. The introduction is by Andre Norton, at the time a very successful author. 

Cherryh, in that novel, is doing the sort of thing Norton did, but doing it much better. And Norton, to her immense credit, realizes it and is willing to say so. The end of the introduction:
My personal question rises:
“Why can’t I write like this?”
I very much wish that I did.
How many successful writers would have the humility to say that, in print, about a new author?

Friday, June 14, 2019

Why Many Scientific Articles are Wrong

 Suppose you are a professional academic who wants to publish a journal article in order to improve your chance of getting an offer, getting tenure, getting a raise. One way to do so is to produce and write up research that provides support for a novel theory. One problem is that, if the theory is true, it is quite likely that someone else in your field, over the past century or so, has already discovered it and published it, making your result not novel, hence likely to be rejected by the journal you submit it to.

If, on the other hand, your theory is false, the odds are much better that nobody else will have come up with it, found evidence to support it, and published. So if you can produce what looks like good evidence for a false theory, the odds that it will be novel, hence publishable, hence will contribute to your career, is much higher than for a true theory.

How do you produce evidence good enough to be publishable for a result that is not true? 

One solution is a specification search, aka p-hacking. Your theory is that eating onions reduces the risk of Alzheimers disease. To test it, you find a sample of old people who have been tested for symptoms of cognitive decline and survey them on their dietary habits. As a first crude test, you run a regression with degree of cognitive decline as the dependent variable, estimated previous onion consumption as the independent variable.

Unfortunately, that doesn't work—there is no significant correlation between the two. You rerun the regression, this time doing it separately for men and women. Then separately by race. Then by race and gender. Then limited to people over 80. Then to people over 90. Then making your independent variable not estimated onion consumption but whether they report eating onions frequently, occasionally, or not at all. Then do that version for all your racial and gender categories. Then ...

When you are done, you have run a hundred different regressions, testing different variants of the theory that onions are protective against Alzheimers. You are gratified to discover that three of them are significant at the .05 level, with the right sign. You pick the best one and publish it: "Cognitive Effect of Self-Reported Onion Consumption on Elderly Afro-American Women."

The fact that a regression result is significant at the .05 level means that, if your theory is not true, the chance that the evidence in favor of it will, by pure chance, be as good as what you found is only .05. It follows that, if your theory is false, a hundred separate experiments can be expected to produce about five that support it at the .05 level.

In this version of the story, the researcher is deliberately trying multiple experiments and only reporting the results that support his theory. The same effect could occur via multiple experiments by multiple researchers. If a hundred different researchers produce one experiment each, all for false theories, about five will show evidence for the theory at the .05 level. 

And get published.

Monday, March 25, 2019

Project I: Why do States Spend Money?

I have a file drawer full of research projects that I at some point started and then abandoned. Since I am unlikely to ever get back to them I thought it would be worth describing some here in the hope that someone else, earlier in his career, would be interested in reviving them, perhaps for a PhD thesis or a book. This is the first such post.

At a crude level, there are two theories of government expenditure. One is that it is determined by the need for government services. The other is that it is determined by the ability of the government to get money. It would be interesting to know the relative importance of the two in the real world.

One obvious test is the behavior of government finance before, during, and after a war. The war sharply increases the need for government spending. Its end eliminates most of the need but leaves standing the higher taxes used to pay part of the cost of the war. On a pure need theory, one would expect government expenditure to fall back to something close to its pre-war level. On a pure revenue theory, one would expect expenditure to remain high—not as high as during the war, when it was financed in part by borrowing and/or inflation, but at least as high as the taxes enacted during war time would support.

That is one approach to the question, but I thought of another. Different U.S. states have different sources of revenue, different tax structures. Different taxes respond differently to exogenous changes such as inflation. If a state is financed by a progressive income tax, inflation pushes taxpayers into higher brackets and so raises real revenue; if prices and incomes double, tax revenue should more than double. If, at the other extreme, a state is financed by regressive income taxes or by property taxes in a system where reassessment of property values is infrequent, inflation should reduce real revenue; if prices and incomes double, tax revenue should less than double. Keeping tax laws is easier than expanding them, so, if expenditure is driven by the availability of revenue, we would expect the first sort of states to have real expenditure increased, the second sort to have it decreased, by inflation. One could do a similar analysis for other changes in the economic environment that could be expected to change, in one direction or another, real revenues, and then see how the expenditure of states was affected by those changes.

To test the alternative, need, hypothesis, you need changes that affect needs for revenue. The largest expenditure of state and local governments is schooling. The cost of schooling largely depends on the number of school age children, which changes over time. On a need theory, when the fraction of the state’s population that is school age goes up, as it did for (I think) all states as the baby boom reached school age, state expenditures should go up. When it goes down, as it did in the years when the baby boom was coming out of the schools and onto the labor market, it should go down. While this effect would apply to all states, its strength should depend on how large a fraction of state expenditure goes to schooling. And other changes that affect the need for state expenditure may vary more across states.

For both hypotheses, the best evidence would be differences in what happened in different states, since that eliminates causes you are missing that affect all states equally, such as changes in technology that  make schooling or tax collection more or less costly. But you would also want to look at changes that affected all states similarly, such as demographic changes that affected the fraction of the population of school age.

That’s the project. Calculate, for each state, how real revenue would be expected to respond to changes in its environment. Calculate, for each state, how the demand for government services would be expected to respond to changes in its environment. See which plays how large a role in predicting what actually happened.

I have described the project from a U.S. point of view but it could also be done for Canadian provinces, Indian or Australian or Brazilian states, or as an international comparison—perhaps with the price of oil as an important exogenous variable.

Saturday, February 23, 2019

How to Milk an Almond, Stuff an Egg, and Armor a Turnip now out as a Kindle

Some time back, my wife and I published our medieval cookbook, How to Milk an Almond, Stuff an Egg, and Armor a Turnip. In addition to making it available as a paperback on Amazon, I also put a pdf of it up on my web page for anyone who wanted to download.

It recently occurred to me that it would get much more visibility on Amazon, and that some people would find a kindle more convenient than a pdf. I put the question to people on Facebook, and quite a lot of them said they would like it as a kindle. 

So I converted my Word document to a kindle, using Calibre, a free conversion program. It's a nice program, and their technical support is fast and helpful. Despite that I ran into a lot of different problems, with the result that the conversion took something like ten to twenty hours, about ten times as long as I had expected. But it's now done and up on Amazon, and has sold thirteen copies in the last two days.

For those not familiar with it, the book consists of all of the cooking material from the Miscellany that Elizabeth and I have self-published for a very long time. It contains over three hundred medieval and renaissance recipes, in each case with the original (or a translation) and our worked out version. In addition there are articles on topics related to period cooking. I assume that most but not all of our customers will be fellow SCA members.