[R] acos(0.5) == pi/3 FALSE

[Charles C. Berry]

On Tue, 19 Sep 2006, Johannes Hüsing wrote:

> Peter Dalgaard:
>> Ben Bolker <bolker at zoo.ufl.edu> writes:
>>>          1. compose your response
>> I've always wondered why step 1. - often the time-consuming bit - is not
>> listed last.
>
> The advice applies to the situation when answering immediately would be
> your knee-jerk reaction. It is assumed that actually composing and sending
> the mail would take very little time and thought, whereas coming around to
> answering it after runif(1)*4 hours would take considerably more time, even
> when mulitiplied with the probability that you are still the first one.
>
> Looking at the submission times of questions and answers in this
> particular case, though, I would be upset if the helpful guys actually
> used this algorithm. Most of the answers were submitted after 3.5 to 4 h
> time, thus revealing a possible flaw of the random number generator
> underlying runif().

Johannes,

Turn on 'full-headers' in your email reader.

Most of the replies were submitted within 20 minutes of the posting of the 
original query by the list-serv (to me and I assume to others) and several 
that said essentially the same thing were posted within the first 10 
minutes, I recall.

The list-serv held the initial email for a couple of hours before passing 
it on. The replies are processed more rapidly, being held at most a few 
minutes each.

Given the initial hold placed on that email, runif(1)*4 hours would have 
increased the overall response time (from time of initial posting to time 
of first response) by less than 25% (with high probability). And would 
have saved several respondents from having to type up their replies.

In this case even runif(1)*20 minutes would likely have cut the response 
traffic to one or two and would have increased the overall response time 
by less than 10 minutes.

Chuck

>
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Charles C. Berry                        (858) 534-2098
                                          Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	         UC San Diego
http://biostat.ucsd.edu/~cberry/         La Jolla, San Diego 92093-0717