Archive for the Kids Category

Brussels snapshot #2 [jatp]

Posted in Kids, pictures, Running, Travel with tags , , , , , , on June 17, 2018 by xi'an

La Rochambelle, 15000⁺ women in pink! [38:53, 118th & 8th V2…]

Posted in Kids, pictures, Running, Travel with tags , , , , , , , , , , on June 16, 2018 by xi'an

Aessentially every year in the past decade, I have run the 10K in Caen for Courants de la Liberté, with 5000⁺ runners, on once again a new route, still completely intra muros in the city of Caen, and mostly flat, with highlights Guillaume’s medieval castle and Men Abbey,  the gothic St. Pierre church,  and a few other churches. It went reasonably well if not great (although I ran the first 5K’s in 19:02) as I ended up at a mediocre position (8th) in my category, which is not surprising with some runners now 9 years younger than I! (The runner next to me is the first V3.) Weather was much better than last year, if still too hot. I however primarily want to congratulate my mom and my mother in-law for walking the 6⁻ km Rochambelle the previous evening  in great cheer despite the rain and the crowd. I could not spot them on the picture above…

 

prior against truth!

Posted in Books, Kids, Statistics with tags , , , , , , , on June 4, 2018 by xi'an

A question from X validated had interesting ramifications, about what happens when the prior does not cover the true value of the parameter (assuming there ? In fact, not so much in that, from a decision theoretic perspective, the fact that that π(θ⁰)=0, or even that π(θ)=0 in a neighbourhood of θ⁰ does not matter [too much]. Indeed, the formal derivation of a Bayes estimator as minimising the posterior loss means that the resulting estimator may take values that were “impossible” from a prior perspective! Indeed, taking for example the posterior mean, the convex combination of all possible values of θ under π may well escape the support of π when this support is not convex. Of course, one could argue that estimators should further be restricted to be possible values of θ under π but that would reduce their decision theoretic efficiency.

An example is the brilliant minimaxity result by George Casella and Bill Strawderman from 1981: when estimating a Normal mean μ based on a single observation xwith the additional constraint that |μ|<ρ, and when ρ is small enough, ρ1.0567 quite specifically, the minimax estimator for this problem under squared error loss corresponds to a (least favourable) uniform prior on the pair {ρ,ρ}, meaning that π gives equal weight to ρ and ρ (and none to any other value of the mean μ). When ρ increases above this bound, the least favourable prior sees its support growing one point at a time, but remaining a finite set of possible values. However the posterior expectation, 𝔼[μ|x], can take any value on (ρ,ρ).

In an even broader suspension of belief (in the prior), it may be that the prior has such a restricted support that it cannot consistently estimate the (true value of the) parameter, but the associated estimator may remain admissible or minimax.

and it only gets worse…

Posted in Kids, pictures with tags , , , , , , , , , , , , , , , , , on June 3, 2018 by xi'an

“Donald Trump’s attacks on the press are “out of control” and damaging “the civic life and debate of the country”, the editor of the New York Times said on Sunday. Dean Baquet was responding to a tweet in which the president attacked his main rival. “The Washington Post is far more fiction than fact,” Trump wrote. `Story after story is made up garbage – more like a poorly written novel than good reporting. Always quoting sources (not names), many of which don’t exist.’ ” The Guardian, April 8

The Trump administration is expected to announce today a rule that would strip federal funding from clinics that provide abortions or refer patients to places that do. The rule, a return to a Reagan-era policy, is a victory for social conservatives. It’s also a jab at Planned Parenthood, which serves 41 percent of women who receive federally funded family planning services.2  NYT, May 18

“Donald Trump pulled the US out of the landmark nuclear deal with Tehran on Tuesday, moving to re-impose sanctions on Iran and defying pleas from close allies who had called for the agreement to be preserved. The decision marks a bitter defeat for America’s European allies, who have spent months beseeching Mr Trump to stay in a deal that he has denounced as “insane”. Critics warned it would further endanger stability in the Middle East. ” FT, May 8

“Donald Trump has slammed the gun laws of major US allies, claiming foreign countries could better protect their citizens – and possibly stop terrorist attacks – by loosening their gun control laws. In a speech to the NRA Leadership Forum, Mr Trump sought to reassure members of the US’s largest gun rights lobbying group of his support for the Second Amendment, after briefly expressing support for gun control measures in the wake of a school shooting in Florida.” The Independent, May 5

 

plastic oceans

Posted in Kids, pictures with tags , , , , , , , , on May 28, 2018 by xi'an

running by Kenilworth Castle [jatp]

Posted in Kids, pictures, Running, Travel with tags , , , , , , , , , , , , , on May 26, 2018 by xi'an

Last week, while in Warwick, I had a nice warm afternoon run around Kenilworth in the fields with Nick Tawn, who brought us to this view of the castle from the West, by a former shallow lake called The Mere [lexicographically connected with La Mare rather than with La Mer!]. It also exposed the fact that my first and only visit to the castle was in the summer of 1977, with my pen friend from Birmingham. This was also the summer when Star Wars was released in Britain, including Birmingham where we first saw it…

repeal!

Posted in Kids with tags , , , , , , , , on May 24, 2018 by xi'an