From: c23st@kocrsv01.delcoelect.com (Spiros Triantafyllopoulos)
Newsgroups: rec.autos
Subject: yet another consumer reports article (Re: Before Buying Japanese.)
Date: 22 Jan 93 18:13:30 GMT
Distribution: na
Organization: Delco Electronics Corp.

In article <1993Jan22.142044.20423@magnus.acs.ohio-state.edu> jnielsen@magnus.acs.ohio-state.edu (John F Nielsen) writes:
>>Unless CR can prove that they have used a sample population
>>representative of the actual population of course...
>
>Why is that necessary for what they are trying to show. Unless the
>people answering the questionaires are morons or like to lie, the
>data is useful, it is not that hard to know when you got a repair.

Because, very simply, it is not correct. In order for the statistics
to be correct they would have to make sure that several things happen:

a. questionnaires are mailed to people in proportion to car ownership
   (or market share)
b. response rates are similar to mailing rates
c. response rates are accurate as far as problem reporting goes
d. statistical methods are followed properly

a. is not the case (I would bet that CR readers do not represent
   a balanced car ownership group, i.e. 70% domestic, 30% import)
b. is not the case if a. is not the case and at either case :-) 
   I don't think they bother to check
c. is not the case due to 'expectation management' and many other
   factors (i.e. consumers understanding what is wrong with their
   cars, trusting dealers to tell them and fix what is wrong, etc)
d. I would not know. They'd have to adjust the data for things like
    driving conditions, mileage, proper/improper servicing, etc)

The only true source for a,b,c is manufacturers data for warranty
claims for repairs (initially) and service records (after
warranty/uncovered). Of course noone will provide such data. 

Again, I'm not a statistician (married to one though) but have taken
enough classes in statistics to see some of the obvious flaws; entire
CHAPTERS in statistics texts are devoted to incorrectly used stat
methods. 

>>CR is great for getting you to THINK about features, but I have had
>>serious questions about their credibility ever since I bought a
>>lawnmower based on what they said... Just like in cars, they were
>>quick to point out flaws or potential flaws in SOME brands but MAJOR
>>flaws were sometimes ignored in SOME brands.
>
>So, what did they mess up on? 

In my case, a couple of things. One was that the lawnmower in question
was WAY too HEAVY after grass clippings were collected; its engine
was 4.5 hp instead of 5; oil changes are quite messy due to drain plug
placement; owner's manual was written by people whose native tongue was
CLEARLY not English, making it impossible to understand how to do even
simple procedures); transmission with only two gears (instead of more) which
are not spaced properly, i.e. low is too slow, even fast is not fast enough;
lack of manouevrability (jockey-ing)....

Most of these things were pointed out for OTHER mowers, but not for the
knight-in-shiny-armor they rated tops. 

Whatever they pointed out as a plus was a plus, so I'm sure they tested
the mower; but in their trivia-pick mode they should have picked the wrongs,
too.

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]