Yenya's World

Tue, 21 Apr 2009

Statistics Problem

Is there any statistician reading this blog? Can you recommend any statistics community (web forum, mailing list, anything) where I can ask questions about one problem I am currently trying to solve? For those with login to IS MU, the description will for some time be also in the discussion forum of Faculty of Science. The problem is this:

I have a random variable with probability of exp(-a*t) for some constant a and the time t (think radioactive decay, but the real problem is something different). The problem is to calculate the constant a from the observed data.

The measurements I have are in the form of a set of pairs (ti, + or -), with the following meaning: At time 0, take a brand new "i-th atom", verify that it is not decayed, wait for the time ti, and look at it again. If the atom has not decayed yet, add a (ti, +) pair to the set of measurements. Otherwise, add (ti, -). Continue with the next new atom an the next time ti+1.

Note however, that the times t_i are given to me from the outside, I cannot choose them, and they do not have any particular distribution (e.g. being equally distributed between time of zero and some large number). Also, the number of measurements is quite small (several hundreds at most).

You can download a Perl script for generating the test data, the test data (100 rows), and the large test data (10,000 rows) generated by this script. Can you somehow compute which constants a have been used when generating these sets of data? If so, how could it be done? And how can I estimate how accurately the exp(-a*t) curve fits the real data?

Section: /computers (RSS feed) | Permanent link | 4 writebacks


I live in a country with population of about 10 milion, with the capital Prague with about 1 milion inhabitants. Today's rant will be about narrow-minded journalists living and working in Prague.

I frequently ran into a blatant cases of pragocentrism. For example in almost every traffic news in a country-wide and state-funded radio station Radiožurnál they use formulations like this: "there is an accident in the Brno motorway in a direction to Brno". WTF? Which of the three motorways heading to Brno do they mean? The D1 from Ostrava? The D2 from Bratislava? No, of course they report from the perspective of people living in Prague, so naturally with "the Brno motorway" they mean "the motorway from Prague to Brno".

Another one was a few days ago, also on Radiožurnál. They were doing an interview with a candidate for the minister of the interior (who currently works as the head of the anti-monopoly office, the institution located in a barren countryside far away from Prague, namely in Brno :-). The first question was "Have you already get used to living in Brno instead of Prague?". Mr. Pecina replied something like: "I don't understand the question - I am from Frýdek-Místek, I have been living there for almost all of my life, except only one short stay in Prague.". The journalist had naturally expected that every important person must have been from Prague. That said, the journalist was really stupid anyway and she manifested it several other times during that interview.

Another case of Pragocentrism is more general. In the main news of the Czech TV (also state-funded), they often report about Prague-local things (such as some affairs of mayor of some part of Prague or even of a mayor of Prague, building some tunnel or some stadium in Prague) during the main part of the news, even though they have a separate part "news from the regions". Also when doing a coverage of a country-wide event such as elections, they report about the situation in Prague, and then they say something like "and now we will look into the regions". WTF? Prague is not a region? Why should the Prague-local news be forced to us by state-funded media as something important?

I know I probably sound like some women-rights or some minority-rights activist with a well-developed inferiority complex, but hey, about 90 % of citizens of this country do not live in Prague! Journalists, keep that in mind, please. My dear lazyweb, is a ${your capital}-centrism also present in your country? Is there even a Brnocentrism from people living in Brno towards people living near Brno?

Section: /personal (RSS feed) | Permanent link | 10 writebacks

Fri, 03 Apr 2009

HTML <button> Tag

So I wanted to upgrade the form we use in IS MU in many places for selecting a printer, splitting the "print" and "download PDF" functionality to separate buttons. The problem is how to make it as backward-compatible as possible.

I basically wanted to have two buttons with the same name="..." attribute, and distinguish between them by their value="..." attribute. I have came across the cool new (for me anyway :-) HTML tag <button>, which does exactly what I want. I am able to use my own machine-readable value="...", and put the button label (localized) inside the <button>...</button>.

Except that it does not work in MSIE. That parody of a browser does not send back the value="..." attribute contents, but rather inner text of the <button> tag for all buttons in the form, not just for the actually clicked one. Stupid MSIE, die already.

Section: /computers (RSS feed) | Permanent link | 2 writebacks


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