[gov2001-l] 2c question (fwd) - Gov2001

23 Feb 2003

you don't need rbinom in 2a. sorry. it was my typo.

Kosuke

---------- Forwarded message ----------
Date: Sun, 23 Feb 2003 22:16:34 -0500
From: Ryan Davies &lt;rdavies(a)fas.harvard.edu&gt;
To: Kosuke Imai &lt;kimai(a)fas.harvard.edu&gt;
Subject: Re: [gov2001-l] 2c question

Yeah, but I'm not sure where we'd use rbinom in 2a.

----- Original Message -----
From: "Kosuke Imai" &lt;kimai(a)fas.harvard.edu&gt;
To: "Ryan Davies" &lt;rdavies(a)fas.harvard.edu&gt;
Sent: Sunday, February 23, 2003 10:12 PM
Subject: Re: [gov2001-l] 2c question

...
  you can use dbinom but not rbinom. of course, if you
have already written
 your own dbinom, that's fine too: it's just one line function. you also
 cannot use rt. is that clear?

 Kosuke

 On Sun, 23 Feb 2003, Ryan Davies wrote:

 > Do you mean that we can't use dbinom() either, for 2a?
 >
 > -Ryan
 >
 > ----- Original Message -----
 > From: "Kosuke Imai" &lt;kimai(a)fas.harvard.edu&gt;
 > To: "Phillip Y. Lipscy" &lt;lipscy(a)fas.harvard.edu&gt;
 > Cc: "Gov 2001" &lt;gov2001-l(a)fas.harvard.edu&gt;
 > Sent: Sunday, February 23, 2003 8:41 PM
 > Subject: Re: [gov2001-l] 2c question
 >
 >
 > > Here are some clarification as to what built-in functions you can and
 > > cannot use. basically, you shouldn't use rbinom and rt.
 > >
 > > 2a. write your own function. don't use rbinom
 > >
 > > 2b. don't use dbeta.
 > >
 > > 2c. you can use rbeta and the function you wrote in 2a. don't use
rbinom
...
  > >
 > > 3a. write your own function. don't use rt
 > >
 > > 3b. you can use the function you wrote in 2a. don't use rbinom
 > >
 > > Kosuke
 > >
 > > On Sun, 23 Feb 2003, Phillip Y. Lipscy wrote:
 > >
 > > > We're running into trouble with taking draws from the beta
distribution
...
  > on 2c.
 > > > Our function for 2b gives us nice looking curves, but when alpha &
beta
...
  > < 1,
 > > > the curve goes to infinity at the extremes.  So when we take draws
from
...
  > the
 > > > beta distribution, how are we to weigh the probability of those
infinite
...
  > > > extremes?  rbeta() seems to give a
result consistent with the shape of
...
  > the
 > > > curves - i.e.
 > > >
 > > > for (alpha & beta = really small) --> returns 0 and 1s
 > > > for (alpha & beta = really big) --> returns values very close to
0.5
 > > >
 > > > Or, basically, is there a forumla for the probability mass function
for
...
   a beta

distribution?

 Thanks,
 Phillip

 -------------------------------------------------
 Phillip Y. Lipscy
 Perkins Hall Room #129
 35 Oxford Street
 Cambridge, MA 02138
 (617)493-4893 DORM
 (617)851-8220 CELL
 lipscy(a)fas.harvard.edu
 http://www.people.fas.harvard.edu/~lipscy/

 First Year Student, Ph.D. Program
 Harvard University, FAS, Department of Government
 -------------------------------------------------

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