The garden of forking paths: Why multiple comparisons can be a
problem, even when there is no “fishing expedition” or “p-hacking” and
the research hypothesis was posited ahead of time
 Andrew Gelman† and Eric Loken‡ 14 Nov 2013

Researcher degrees of freedom can lead to a multiple comparisons
problem, even in settings where researchers perform only a single
analysis on their data. The problem is there can be a large number of
potential comparisons when the details of data analysis are highly
contingent on data, without the researcher having to perform any
conscious procedure of fishing or examining multiple p-values. We
discuss in the context of several examples of published papers where
data-analysis decisions were theoretically-motivated based on previous
literature, but where the details of data selection and analysis were
not pre-specified and, as a result, were contingent on data.



Susan Niederhoffer writes:

Victor Niederhoffer writes:

How many of  this typical spec party enjoyed this opus from the greatest piano player of our generation.



News from NYC

July 22, 2020 | 1 Comment

Susan Niederhoffer writes: 

from a facebook friend recovering from cancer and now in NYC:

Out and about. My walk home from Lymphedema Treatment (excellent therapist by the by) before jumping into a taxi with a 70 year old driver from Cairo (who after 31 years is returning to Egypt because of the current situation here).

I must say on my leisurely walk home I began to have very bad feelings about the city. With all the many many businesses and restaurants who have not re-opened and who knows if they ever will again, the front of their stores and the city sidewalks are embarrassingly dirty. Why doesn't DeBlasio employ people to clean/sanitize the streets! He'd be accomplishing several things: employ people, keep us safe & pick up spirits. I feel violence in the air. So many people have been out of work too long, are now being evicted and are/will become desperate.

I'm very afraid for my city. It doesn't look good. On a personal note, I'm leaving just in time. This is not the place to be in the coming future.

Hernan Avella writes:

This is good, the old and feeble should leave, rents and housing come down, a new crop of rascals occupy and the wheels of commerce keep turning

Ralph Vince writes:

Who who in their right mind is going to return to that City? clearly the first thing that needs to be cleaned up there is leadership.

in the meantime the wheels of commerce can continue in New York City… The way it stands Hernan is right…the wheels of commerce in midtown for check cashing joints, pawn shops, convenience stores, liquor stores. How about Lotto? That sets you up is our world finance hub doesn't it? How about some girly joints in midtown when that be infinitely better than the boarded-up barbed wire dump that it is now? 42nd Street would be a good place for used car lot tear down what they're putting up at 42nd and Vanderbilt I've long thought a used car lot belongs on 42nd Street. I'm going to barbecue joint on 5th avenue? 

And if New York needs a model I'll go take some pictures of Cleveland 40 years after Dennis kucinich, it would be like peering into the future. We can turn the Bloomberg complex into a Goodwill supercenter!

hgiffford writes:

Those Detroit are said to be fearful because the first generation of Americans who don't care about owning a car, and who would just as soon not own a car, are sitting in cafes typing on their laptops all of the US now.

However, there is one city in the US where it is easy to live without a car

Ralph Vince writes:

What happened in NYC is egregious in an "off the meter" sense; I don;t recall ever, in the history of the City, such an event transpiring, or implicitly invited by leadership there.

This is not a "big, scary prediction." There are other factors in play now, bigger than the abdication of protection of the city,  that conspire to make the uphill grind for NYC greater than before. There is a giant human migration out of many locales, NYC being one of them, where the confluence of a number of factors, e.g., greater remote work, etc.,further promote individuals and corporate citizens out of the City in search of greener pastures in smaller metro areas. The scale of this is hard to measure this early, it seems something whose time has come but needed the events of recent months,  and it doesn't play in favor of the City recovering any time soon. As I said,I for one will not return until some semblance of sanity in leadership returns, and proves itself out. Many others I correspond with feel similarly. Nothing changes while nothing changes.

I am not a charlatan of sorts, as you seem to imply. I do my homework - more than anyone else I know.  I stand by what I "predict," and I put my own money on it.

Adam Friedman replies:

I don't think you're a charlatan at all. I know you've been successful putting your money where your work/mouth is over the years. That deserves respect.

It just appears over the last few months each missive from you has a more exclamatory and outlandish prediction than the last– whether it be about markets or the now eternal damnation of NYC. It appears to be self-inflicted confirmation bias that runs deep.

Nothing from this side is a comment about how hard you work, the quality of your work, or your track record. 



The following is from Gary Becker and Richard Posners' Blog. It is a piece by Becker on Milton Friedman, who sadly passed away this month. [Read the NYTimes Obituary]

I will not dwell here on what a remarkable colleague he was. However, I do want to describe my first exposure to him as a teacher since he enormously changed my approach to economics, and to life itself. After my first class with him a half-century ago, I recognized that I was fortunate to have an extraordinary economist as a teacher. During that class he asked a question, and I shot up my hand and was called on to provide an answer. I still remember what he said, "That is no answer, for you are only restating the question in other words." I sat down humiliated, but I knew he was right. I decided on my way home after a very stimulating class that despite all the economics I had studied at Princeton, and the two economics articles I was in the process of publishing, I had to relearn economics from the ground up. I sat at Friedman's feet for the next six years– three as an Assistant Professor at Chicago– learning economics from a fresh perspective. It was the most exciting intellectual period of my life. Further reflections on Friedman as a teacher can be found in my essay on him in the collection edited by Edward Shils, Remembering the University of Chicago: Teachers, Scientists, and Scholars, 1991, University of Chicago Press……

To conclude on a more personal level, I was most impressed by Milton Friedman's sterling character–he would never soften his views to curry favor–his perennial optimism, his loyalty to those he liked, his love of a good argument without any personal attacks on his opponents, and his courage in the face of prolonged and virulent attacks on him by others. I cannot count the number of times I participated with him in seminars, nor how many visits my wife and I shared with Milton and Rose, his wife of almost 70 years. Rose, a fine economist, would not hesitate to differ with her husband when she believed his arguments were wrong or too loose. When I spoke on the phone with him last Monday, he sounded strong and a bit optimistic about his health, even though he had just returned from a one-week hospital stay with a severe illness, an illness that a few days later took his life. Although his ideas live on stronger than ever, it is hard to believe that he is not here. I can no longer seek his opinions on my papers, but I will continue to ask myself about any ideas I have: would my teacher and dear friend Milton Friedman believe they are any good?

Sam Humbert adds:

I also like these vignettes from Ben Stein:

When I was a Columbia undergrad in the early '60s, Friedman taught there for a year and was a good friend to me. He even used applied statistics to save me from romantic desperation when I was worried about replacing a girlfriend. If there were only one right woman for every right man, he advised, they would never find each other. Another time, he stopped me from crossing against the light on Broadway and 116th Street, telling me, "Why risk your whole life to save 10 seconds?"


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