From: thf2@ellis.uchicago.edu (Ted Frank)
Subject: Re: fraternities
Reply-To: thf2@midway.uchicago.edu
Organization: University of Chicago Computing Organizations
Distribution: na
Date: Wed, 15 Apr 1992 16:45:26 GMT

In article <Adv538e00WB8I2TJdM@andrew.cmu.edu> es2q+@andrew.cmu.edu (Erik Warren Selberg) writes:
>thf2@ellis.uchicago.edu (Ted Frank) writes:
>> In article <sdusExq00VpKM8=J4f@andrew.cmu.edu> es2q+@andrew.cmu.edu (Erik Warr\
>> en Selberg) writes:
>> For the same reason we can say that smoking two packs a day makes you
>> Y number of times more likely to get lung cancer.  Ceteris paribus,
>> being in a fraternity makes you X number of times more likely to commit
>> rape.
>
>Not quite.  As mentioned in a previous post, there are several
>different types of cigarettes, as there are several different types of
>fraternities.  The general statement "Smoking two packs a day makes
>you Y times more likely to get lung cancer" isn't necessarily true.
>Ceteris paribus, The general statement "being in a fraternity makes
>you X number of times more likely to commit rape" isn't necessarily true.

If you would prefer, we can use the analogy, "being a male under the
age of 21 makes you Z more times likely to have an auto accident."
If you'd like to explain to an insurance company why that isn't
"necessarily true," ceteris paribus, I'll be happy to watch them laugh
you out of the office.

>> Good logic.  You know of one statistic that can be misused, therefore
>> all statistics are misused.  Talk about overgeneralizing.  
>
>No, the logic here was I know of one statistic that can be misused,
>therefore the possibility exists that another statistic can be
>misused.

But this adds nothing new to the discussion.  Any form of communication
can be misused, including attacks on statistics as well as statistics.

>> Perhaps you can show why the X-times-likely statistic is invalid, rather
>> than dismissing it out of hand?  You did such a wonderful job with that
>> Utah statistic, you should have no problem with this one.
>
>Using this statistic (copied from some other post):
>
>From,   U.S. News and World Report ``When sex is the issue.'' 
>        v 111 pages 34+ Oct 7 1991      
>
>        ``A 1990 study by the University of Illinois at Urbana-Champaign
>        concluded that 34 of the 54 reported sexual assaults were by
>        fraternity men, even though they represent just a quarter of
>        male students on campus.''
>
>now, this statistic says that any given rape at UI-UC has a .62
>(34/54) probability of being by a fraternity member.  This statistic
>by itself doesn't mean much -- what you want first of all is the
>confidence interval, using H0 = E[rapist is a fraternity member] ==
>.62.  (if some stats god out there could figure this one out, I'd
>appreciate it).

The null hypothesis would be that 13.5 of the reported rapes were
committed by fraternity members.  Thirty-four isn't within the
confidence interval, it's well over three standard deviations away.

>How can this statistic be misused?  Well, first off, we only know of
>_reported_ rapes.  There was a nice post earlier on about that.

Indeed, one which Ethan Miller and I very nicely refuted.  You're talking
about a huge gap here, one which is either being caused by fraternities
being much more likely to rape or fraternity rapes being much more likely
to be reported.  Given the sociological and psychological studies on the
issue, there's a lot of support for the former and I have yet to see any
support for the latter (and in fact, I've seen evidence that the
reverse is true, that fraternity rapes are *less* likely to be reported.)

>Second, the statement states they were "reported sexual assaults"
>rather than "people convicted of a sexual assault."  Thus this
>statistic is not too useful for determining my inclination to commit
>rape, just the inclination of someone for percieveing it as such.

Cross-apply the arguments Ethan and I made about the nature of
reported rapes.  If anything, as I've explained before, it's *less*
likely that the fraternity rape will be perceived as such.
In addition, we've seen both a law student and
a lawyer on this thread explain why it is well-nigh close to impossible
of getting a conviction for a fraternity rape, which is a huge chunk of
the reason why they're a problem -- if fraternities were held accountable
for the rapes they committed, it wouldn't be half of the problem it is.

>Finally, we'll just assume that 62% of the rapes at UI-UC are indeed
>committed by fraternity members.  What does this say about Carnegie
>Mellon?  not much -- it's kind of like getting stats on young male
>drivers from the USA and using those statistics on youg male drivers
>in Germany.  There isn't necessarily any correlation.

I think that there is a greater difference between the US and Germany
than between UI-UC and CMU.  Certainly the UIUC-CMU difference is smaller
than the UPenn-UIUC difference, and studies at Penn have had similar
conclusions.  (And I'd bet you'd find that the stats on
young male drivers are fairly accurate when applied to Germany.)
-- 
Ted Frank          + "He wanted to be the car rather than the thimble or the
1307 E 60 St, #109 +  hat."  -- District attorney explaining Marc Cienkowski's
U o' C Law Skool   +  murder with bow and arrow of Michael Klucznik in
Chi, IL 60637      +  Doylestown Borough, PA over a game of Monopoly.
Newsgroups: soc.college