From: c23st@kocrsv01.delcoelect.com (Spiros Triantafyllopoulos)
Newsgroups: rec.autos
Subject: Re: yet another consumer reports article (Re: Before Buying Japanese.)
Date: 26 Jan 93 19:57:35 GMT
Distribution: na
Organization: Delco Electronics Corp.

In article <1993Jan26.152710.2253@magnus.acs.ohio-state.edu> jnielsen@magnus.acs.ohio-state.edu (John F Nielsen) writes:

[stuff regarding validity of CR stats deleted]

> What you are doing it taking the community of people who drink Folgers,
> Maxwell House, and Hills Bros and comparing them to each other. 
> In other words, you are already looking at people with type A personality

But, we have no idea *how much coffee* each of our type A drinkers is
drinking; or, if they're taking it with donuts, muffins, Cuban cigars,
or Marlboros. Or whether they drink 5 cups in one shot or spread out
over the day. Or how much ground coffee they use per mug; Or the
drinkers' predisposition to heart disease, diabetes, etc.

Just as we don't know if some cars were babied while some cars were
abused (intentionally or not), driven in Florida/Minessota, etc.

> In this case, you are already looking at people who want to respond
> to the CU questionaire.

Notice 'want to respond'. Studies have proven that dissatisfied customers
'want to' respond much more than satisfied customers 'want to'. That
would mean that for (say) every K car with a black donut there *could*
be 10 K cars with red donuts who did not respond. So much for donuts.

> >There is also the issue of sample size; how many CR readers drive K-cars
> >vs. Accords? and out of these K-car-CR-readers, how many respond vs
> >how many Accord-CR-readers? Out of how many? and in what proportions?
> 
> First off, most people do not buy cars because they think it is
> going to break down. And, it is not that hard to know when your car 
> broke down. And, most people are not pleased that their car breaks
> down.

While it is not hard to know that the car broke down, it can be hard
to the non-car enthusiasts to judge what component failed, and,
whether it failed because of abuse/misuse or because of normal wear
and tear. I.e. for a Honda owner, a brake job every 30,000 miles is
routine. For MY Honda it ain't.  (I don't consider it routine). So
what does get classified as a breakdown? Do people understand the
significance of preventive maintenance?  Do they INCLUDE preventive
maintenance in their reports to CR? How about routine items (clutch,
struts, mufflers, ...).

We also can't know whether a minor problem escalated into a major
one. It takes only a few basket cases to screw up an otherwise
good score in any case; given a LARGE sample and with proper
analysis methods it will smooth itself out; But we have no idea
of CR's sample size (c'me on, after 10 years of blacklisting
certain cars, CR still finds readers driving them.... :-),
and/or analysis methods. Hence, meaningless.

> An annoying problem is an annoying problem. I don't think it 
> signifiantly matters *what* car you are driving. If the car has
> to be in the shop for a week, you'll be annoyed and remember it.
> Unless you assume people are morons.

No, people are not morons. Sometimes people choose to be upset by
MINOR flaws... And I am glad you brought the shop factor in; do
we judge car brands by COMPETENCE of repairs? Sounds like we should
account for that also. I.e. if my car breaks down and it takes a
week for Dumbo's Import Cars and Farm Equipment to figure out what's
wrong with it, while for the same problem Smart Alek's Honda fixes
it in an hour, does *my* confidence in the car change? you bet it
does. 

This also brings in YET another factor that is not shown in CR stats,
that is, the WEIGHT of the repairs. Weight means that different
types of defects/breakdowns are considered different. Do we brand
a stuck power window switch the same as a rusted thru fender after
one year? Both are 'BODY problems'... 

> >It is simply for the same reason that call-in audience polls are NOT
> >accurate. CR or anyone else has no way of controlling the response
> >rate, or of mapping the responses back to a correct population. 
> 
> It is not necessary to map it back to the population. In other words,
> you don't look at it to determine what the failure rate of the
> population is since it is probably skewed by the readership.  You look
> at it to compare if the Ford Crown Vic is more reliable than the Chevy
> Caprice.

But, if we have no idea over sample sizes (how many of each?), use
(how many Crown Vics are driven by 70 year olds in Florida vs. how
many Caprices are used to tow boats in Wisconsin), and a lot of other
factors (even things like dealer service expectations/capabilities),
all the CR studies say is that "some of our readers with Caprices who
bothered to respond found this and this with their car while some of
our readers with Crown Vics who bothered to respond found that and
that". Again, with large sample sizes these things smooth out somehow
but we *don't* have their sample sizes (or the sampling method :-)).

> So, as I said, for their purpose it is not necessary.	

But it ain't accurate, either. And while sophisticated people can
differentiate between accurate statistics and meaningless anecdotal
evidence, not everybody can. 

And that's the whole point. All some people do is look at CR (or any
other publication), see a couple of pictures of authoritative-looking
folks in white lab coats and sophisticated instrumentation, and it
might as well have been G*d delivering The Commandments to Moses...

Spiros
-- 
Spiros Triantafyllopoulos                    c23st@kocrsv01.delcoelect.com
Software Technology, Delco Electronics       (317) 451-0815
GM Hughes Electronics, Kokomo, IN 46904      [A Different Kind of Disclaimer]