From: mlloyd@westmark.Stanford.EDU (Mike Lloyd)
Newsgroups: soc.bi
Subject: a tiny bit worn out
Date: 13 Nov 92 04:30:33 GMT
Organization: DSO, Stanford University

Yeesh.  Mike resurfaces into netland.  The short absence was caused by a
conjunction of disk problems on westmark, and a *hellish* week.  I set a
midterm, then marked it.  It was exhausting, but the real trial was
dealing with student questions - I'm just too much of a pushover that
way.  On Tuesday, I spent from 11:30 to 8 talking >constantly< to a
shifting sea of faces (usually 5 at a time), with one 5-minute break.
One need only check the level on the whisky-bottle I mentioned last week
to see the effect this has had.

So I've decided (after some thought) to make this a hug-request.  I
reckon I'll be recovered before any could show up, but still, it
couldn't hurt.  You're dealing with one unhappy camper - putting too
much in and getting too little out - but I'm expecting a better weekend.

So the group is thick with threads I want to reply to.  I have about 65
articles on my "reply to if you have time" pile, and not even I have
that much free.  Forgive me if I start where it's easiest.  (Be
forewarned that there is a separate addendum to this post too :-)

tweaver@nyx.cs.du.edu (T.C.Weaver) writes:
: mlloyd@westmark.Stanford.EDU (Mike Lloyd) writes:
: 
: >When I shop for jewellery (often with street-traders), I find I don't
: >want an ankh (bad religious vibes); 
: 
: Hang on, isn't it an Egyptian symbol of life? I wear an ankh suspended from
: a dolphin-ring and chain on occasion.

Oops.  Time to refresh my database.  You are, of course, quite right.
That thoughtless "religious vibe" thang dates back to my Evo days, when
there was much debate about how satanic and evil it was that such an
occultist symbol was on sale, and <horror> some True Christians [*]
bought one without knowing what it was, thinking it a neat twist on the
cross.  I always thought these people were crazy, but still picked up
their distaste for the symbol.  One more piece of old baggage to throw
overboard as the ship sails on.

[*] the people pursuing this point were the kind who could be heard to
estimate the number of Christians in Italy at "around 200".

: >               --The end of confusion is the beginning of death--
: 
: Neat. Yours?

Thanks.  Yeah.  It kinda grew out of the talking I've done with muffins,
or ex-muffins, who talk about how terribly confused they are (about
their sexuality).  I do what I can to point out that, as far as I am
concerned, confusion is a necessary sign of mental health - the only
people without it are either dead or fanatical.  On consideration, I
decided the point could be applied rather more generally than just to
sexuality, although it seems that this particular confusion bothers
people the most.  Why that should be I'm not sure... just another of the
oddities of this human animal.

Anyway, I'll close this with an excerpt from the Exam From Hell.  There
were 5 questions, and the following is the text of Question 5.  It's in
TeX, so aplogogies to non-speakers.  \% just means %, and anything else
starting \ is a command.  Anything surrounded with $ signs comes out as
a pretty math formula.  I enclose it for the text, and your amusement.
If any budding stat-heads out there are fool enough to try it, be warned
that part 3 is, well, a swine.

All hugs appreciated
Mike
----
Question 5: 20 marks

You run a company who manufacture jeans.  You wish to gather information
about people who buy your product, to tailor your advertising more
effectively.  You call your market research company and instruct them to
survey your marketplace, gathering information on significant
characteristics of your buyers.

The company survey 200 customers, and find (amongst other things) that
30 describe themselves as lesbian, bisexual or gay (abbreviated to LBG).

\begin{enumerate}
\item Give a point estimate for the true proportion of your 
customers who are LBG.  What is the standard error of this estimate?
\item It has been suggested that 10\% of the US population will 
identify themselves as LBG.  Is there strong evidence that you have more
LBG customers than you would expect?  To answer this question, perform a
95\% two-tail test, and assume by default that the general population
rate is true of your customers too.
\item You will make a Type II error here if you say that 10\% is a
plausible figure for your customers when it is false; that is, you find
$z=(\hat p -p_0)/SE_p$ is ``small'' (in absolute value) for a given
sample.  Find the probability that a sample of 200 customers gives a
small value of this test statistic when 15\% of the your customers are
LGB.  Here you are to use the hyopthesis that 0.1 is the true value, and
look for 95\% certainty, so that $|z|<1.96$ is the requirement for a
Type II error.  (Hint: use $p=0.15$ in your calculation of $SE_p$, and
note that $\hat p\sim N(p,SE_p)$ )
\end{enumerate}


-- 
Mike Lloyd, B0/1 h- f- t w- g+ k+ s m- e? |    "Bloody nose and burning eyes
      Retro-hippy, music nut, bi and      |  Raised in laughter to the skies"
          backrubber of devotion          |                 - Bruce Cockburn
               --The end of confusion is the beginning of death--