From reading your posts, I get the impression that you are unusually
objective in your observations and descriptions of your automotive
experiences, or at least you really try to be objective. (IMO, that is a
good thing). The only point where I see less than an attempt at total
objectivity is your point that one size truck is "just right" while another
may be too large or too small. IMO, there is demand for the spectrum of
truck sizes and capabilities and the profit opportunities they provide to
the automakers. The reason for the demand may be totally subjective, like
why someone who hauls 2 bicycles would need a full size truck instead of a
smaller one, but the demand is (with higher gas prices, maybe was) still
I have no statistical basis for my opinion, but I think that people who have
a favorable impression of a product are more likely to overlook a design
feature or vehicle characteristic that they might not overlook in a vehicle
that they do not have as favorable impression of. I think Toyota and Honda
have benefited greatly from this phenomenon, if it exists. An example of
this phenomenon is the piston slap that some people have complained about.
The manufacturing and assembly methods that Toyota uses results in very
little variation, and under the same operating conditions and maintenance
history, 2 Toyotas of the same model are very likely to experience the same
problems or lack of problems, which means that the noise that some people
are complaining about and some people do not complain about is likely there
in most, of not all of those models. People who love their cars or trucks
are probably less likely to count the noise as a problem on the survey than
people who are indifferent or are very picky.
They're not asking, "How do you like it?" They are asking a different
question, "How many problems have you had with it?" I could just love my
new Prius even though I had a problem with the power steering pump, a
leak in the truck and a cracked windshield. Or I might hate it even
though it has had no problems.
This is why I can't possibly see how J.D. Power surveys are useful in
determining anything other than initial quality which is what they are
designed to measure. And I actually am a big believer in Porsches, I
just don't think that J.D. Power results mean squat to anyone who's
going to keep their car after the warranty runs out.
replace "roosters" with "cox" to reply.
Powers has a lot of importance. Look at all the advertising revenue it
generates. It is also very important to know what the best car is for those
that keep them for 3 to 6 months. If, OTOH, you intend to keep your car for
5 or 15 years, it has no meaning at all.
Consumer Reports has more meaning to the long term owner.
If the question is, how much service did you need in the first year of
ownership, then JD Powers is the place to look. but when the question
becomes, how much service did you need after 5 years, then Consumer Reports
has the better answer.
----- Original Message -----
Sent: Sunday, June 08, 2008 6:43 PM
Subject: Re: 2008 J.D. Power Initial Quality Study: Porsche, Honda,
Chevrolet among big winners
JD Powers also has a survey that address longer term reliability (3 years).
I suspect this is about as long as is meaningful. After three years I
suspect owner treatment of the vehicles becomes a significant factor in
I've never had much respect for the CR survey results. I've answered them
for years, but think doing so is largely a waste of times. The survey is far
from random and they collect too little information to make the broad
pronouncements given in the magazines. The little circles they display in
the magazine are also misleading. They over emphasize the difference between
I agree, mostly. Any survey is dependent upon the sheer number of
participants/respondants, and the more there are the greater the accuracy of
the data. With any survey, if one throws out the top and bottom extremes of
the response curve, the result should be relatively level and a reasonably
accurate indicator of the overall feeling of the sample group.
I don't think that JD Powers and Consumer Reports will attract significantly
different samples. They might ask different questions, and that might garner
different responses, and this can result in differing views on the overall
feeling of the groups, I don't see that either survey is better or worse
than the other.
I would not follow the advise of the editorial staff too closely, except
that they would have a good feel for the ergonomics, fit & finish, and
comments about "feel good" stuff. They can not address the long term
servicability issues, but they can accurately report on stuff such as noise
in the cabin, relative power and performance, location of cup holders, etc.
But, when actual owners are asked about what they like and dislike about
their cars, I have to give them far more weight for accurate responses.
? The extremes cancel each other out and should not affect
the average in any significant way, assuming the sample size
is large enough.
Sample size per year-model seems about the same for the IQS
and CR surveys. Power is not as forthcoming, IMO, about
sample size per vehicle.
Links at http://www.jdpower.com/autos/car-ratings/ ,
says Power used input from 97,000 car owners for the IQS.
The input covers I guess over 100 different models. (I am
too lazy to count them all up.) So there's input of maybe
around 1000 owners for each model.
J.D. Power's 2007 dependability ratings (for three year old
cars, asking about problems in the last 12 months) use input
from a paltry 53,000 car owners.
CR uses input from 1 million owners, covering 1100
model-years for the past decade. So CR is using the input of
about 1000 owners per model-year. So I'd guesstimate that
CR's input is of higher statistical significance for any
given model-year. Take a few years running where the model
design is known not to have changed a lot, and CR is of much
higher statistical significance.
Sure, the editorial comments are a start and at least as
good as anecdotal reports here.
I suppose the prudent course is to form a "meta-study" of
both the J.D. Power survey and CR's survey.
Which hints at a big CR strength; presentation of the data. With CR
you can quickly see the entire history of each system in each model.
You can quickly spot the year they fixed the transmission or whether
manufacturer X has problems with the first model year of a new design.
It is not random at all. They only survey CR readers, and then only readers
who wish to respond. I've always felt this biases the results of the CR
survey to match the editorial opinions of the CR staff. In recent years CR
has done a better job of massaging the results, but I still think they are
And why do you think the JD Power survey is useless? It is a true random
survey. They collect much more information than CR does.
And you know this because? Does it ever bother you that the results for
different year model of a particular model that should be essentially the
same parts get vastly different reliability ratings in some categories from
year to year?
OK, what exactly do they mean.....I mean besides Excellent, Very Good, Good,
Fair and Poor. For '07 cars, the average problem rate for the worst category
(Body Integrity) was only 3%. What do you suppose the accuracy of the CR
Survey is? I'll bet it is a lot worse than 3%.
So, CR surveys a select group, that is more likely than the general
population to agree with there opinions, they don't provide data on the
number of vehicles of a particular type surveyed, or the even what average
means, yet you think they are highly accurate.....
What benefit is it of CR to massage the responses you and I give to the
survey? Their business is to test stuff and provide the results. You may not
test the same way they do, or come away with the same conclusions, but that
does not change their mission in life.
When you report your experience on your '05 Camry, or whatever, they only
compile that experience with all others reporting on the same car. They
don't care what the response is, they are only interested in the relative
responses so they can derive an average response, then denote it with a
symbol that essentially gives a rating on a scale of 1 to 5.
If they get 100 responses, the sample size is not so large, but if they get
100,000 responses then the sample size is very large and by statistical
standards, very reliable.
No, it does not bother me at all.
You are asking if it concerns me that a Ford Crown Vic a Mercury Marquis and
a Lincoln Towne Car can score differently. No. I suspect the buyers might
have different expectations of quality between a Ford a Mercury and a
Lincoln, and this can feed into the satisfaction each customer has in his
car. It is also possible that the different cars are built to different
standards, and the more costly unit is actually built better. I don't know
the specifics of the response, but if I was in the market for a used car, I
would at least look at the models I was interested in to see what others
were, or were not, happy with, and I would also look at the same car with
different name plates. Mazda CX7 owners might like their car, but Ford Edge
owners might not be so happy. That might be useful information in a Used Car
Actually, they don't select a group at all. They mail out a questionaire to
ALL SUBSCRIBERS, who then complete them and send them in to be tallied.
You are correct in that they (CR) does not provide the sample size, so you
do not know if you are looking at 100 responses or 100,000, or 10. Having
said that, I recall that they do have a minimum sample size, and if they
don't get enough responses, then they put N/A on the table. One or two
people that like or dislike a feature is not a valid response. I don't know
how many responses it takes to get a statistically valid response, but
surely a sample size that is too small does not give valid data.
J.D. Power also only surveys those who wish to respond. I
can't see how the self-selection is any worse.
What motive would CR editors have to massage what CR readers
"Editorial" is way too strong a descriptor for the quality
reviews of the cars (not the matrices of reader experiences)
that CR testers perform. The tests the CR staff does has
results all over the map. Sometimes Ford gets a good rating,
sometimes VW, and so on.
The reader surveys OTOH consistently rate Toyota and Honda
as the best makes of cars.
but I still think they are
Not for Hondas and Toyotas, with the exception of an
occasionally new design, like the Toyota Tundra c. 2004.
Sounds like you have been reading the articles. I do not
have the April issue handy, but what the circles mean is
See my post to Jeff. The "accuracy" of the CR surveys should
be better than that of J.D. Power's dependability survey,
because the sample size per model appears to be larger.
(Neither JD Power nor CR give the exact number of owners per
model surveyed.) You can still argue CR reader bias, I
suppose. Though, come on, what does that mean here? CR
readers are no more likely to ignore car problem than anyone
else, are they? Or do we want to sample car owners who get a
breakdown and ignore the car for the next two years? Or
those who do not like to maintain their car? You do realize
those who do not follow the maintenance schedule throw every
damn thing off when it comes to surveys, right?
It's mostly going to be differences between two models that
are statistically significant, meaning it's reasonable to
conclude another car randomly chosen from a population of
this model will perform X better than another model with a
Nor does J.D. Power state exactly how much input it had for
Plus, for dependability J.D. Power looks only at three-year
old cars, by all indications from a sample arguably as
self-selected as CR's.
Not true. For instance, for 2002-2006 Camrys, the quality of the suspension
varied from very good to excellent from, almost at random. The fuel system
went from very good to excellent to good without any significant changes to
the design. So did the ratings of body hardware. For some reason, '03 have
worse cooling systems that an other year (but according to the parts
catalog, the parts are the same....). I suppose you are going to point out
that chages from very good to excellent are trival, but then that is my
point. The differences are trivial, probably well within the accuracy of the
survey. CR takes poorly collected data (not random, poor questions),
massages it, and presents it as little circles that really don't mean
anything. At least JD Powers gives you a number (number of problems reported
per 100 vehicels) and at least they start out with a random sample. I
suppose you should stay away from any vehicle with solid black circles, but
how many fall into that category? Do you really think there is much
difference between vehicles that rate good or better?
A large but biased sample is not going to give better results.
Have you completes a CR survey? There is a fair amount of room for
iterpertation of the questions.
So how much statictical difference is there between an Accord and a Camry?
CR predicts a new Camry will have worse than average reliability. A new
Accord will have better than average reliability. What does that mean? If I
buy a Camry instead of an Accord am I likely to have one more problem, or
two, or ten, or twenty? If you can't tell me from the CR predicitions, what
good are they? At least if you look at the JD Power numbers you can get an
idea that the spread between vehicles is very small, much smaller than CR's
reporting methods suggests. In the latest initial quality survey, the
difference between the best vehicle manufacturer (Porsche) and the worst
(Mini) was 0.8 problems per vehicle. In the 2007 Vehciel Dependability
Study, the difference between the most dependable manufacturers (Buick and
Lexus) and the least dependable (Land Rover) was 2.5 problems. This shoudl
tell you that the differences are down in the noise range, and the little
circles that CR uses are trying to divide up very trivial differences into 5
categories. If you start with data that is poorly collected and then try to
use it to indicate trivial distinctions, you are not being fair. At least
with JD Powers, you can see for yourself that most cars are pretty good. I
have no problem with people claiming Land Rovers are less reliable that
Lexi, but I doubt the difference is near as significant as Lexus owners
would like to think.
JD Powers starts out with a random sample. CR starts out with their
Oh my god, good to excellent.
I think the consistency of the almost all red (meaning
good-to-excellent) reliability matrices for Hondas and
Toyotas speak for themselves. Black circles are rare for
them. I am not posting for your benefit. You're dug into a
political belief here. I am posting for others'. Go to CR
and go to J.D. Power. Just do not go to J.D. Power by
You have proved no more bias in CR than in J.D. Power,
either in its questions or in the group it samples.
CR's million owners surveyed per year over ten years trumps
J.D. Power's hogwash 3-year-old vehicle survey of some
People upset with the CR survey results (not just for vehicles) have
been bashing it without any basis for as long as I can remember. CR has
a statistically _huge_ sample, with a statistically tiny margin of
error. Additionally, despite the fact that the surveys are from
subscribers, what's the upside for a subscriber to be honest about their
experience with a Ford, but tell lies about their experience with a
Honda, or vice-versa?
There are often very good reasons for year to year variations on
vehicles that supposedly haven't changed. First of all, there are
changes within design cycles, a 1992 Camry may look almost the same to a
1996 Camry, a 1997 Camry can look the same as 2001 Camry but there can
be significant differences. Besides changes from year to year, there can
be changes as to which factory the majority of vehicles are being built at.
----- Original Message -----
Sent: Tuesday, June 10, 2008 3:09 AM
Subject: Re: 2008 J.D. Power Initial Quality Study: Porsche, Honda,
Chevrolet among big winners
And you know there is a tiny margin of error because? CR may or may
not have a "huge" sample for a particular vehicle. Saying "millions"
sounds impressive, but millions (actually 1.3 million responses for
2007) spread over 10 years of different models implies that some
models may only get a few responses (hundreds or less). CR doesn't
include results below a certain level, but what level is that? The
average number of respondents for a particular year/model is probably
around 500. Do you really think this is enough to provide a tiny
margin of error?
No, but it is my opinion that people who subscribe to CR are likely to
be biased towards agreeing with CR's opinion and tend to color their
responses to match. I am not saying they are lying, or deliberately
miss stating the results just that they are likely to shade their
response to match the CR opinions. When working with relatively small
numbers of responses for a particular model from a select group (CR
subscribers), small errors can appear to be significant when you boil
them down to the little circles. In fact, I suspect that many times
the differences are very small. CR seem to resist publishing the raw
numbers. For comparisons, they go so far as to show difference as
percentage of variation from average for categories of vehicles. This
is potentially just as misleading as the little circles. For instance,
in the small SUV category, the Honda Element predicted reliability of
around 70% better than the average small SUV. The Dodge Nitro has a
predicted reliability of 195% worse than the average small SUV. So no
one should buy a Nitro because it is 265% less reliable than an
Element - right? But what does this really mean? Suppose the average
small SUV has 1 problem. This would imply that the average Honda
Element would have 0.2 problems (or 20 problems per hundred) and that
the average Nitro would have less than two problems. Furthermore, what
exactly constitutes a problems? The CR survey leaves a lot of latitude
to the respondents, and then they don't even let us know how they
factor different levels of problems into the overall reliability.
So this means they have even less good data for a particular model,
making it even less likely the statistical error is "tiny."
A little bit of homework is appropriate before one slanders.
This figure is reported in the annual issue and also at the
CR web site
And on Impala the range is from poor to very poor (mostly the latter.)
Doesn't sound like there is any trouble distinguishing which of these
vehicles has a more reliable suspension system.
And Impala ranges from good to poor. I think you are having trouble
seeing the forest because all the trees are in the way. Step back and
look at the big picture.
So did the ratings of body hardware. For some reason, '03 have
Have you ever heard of a bad batch of parts? Changing suppliers? To
be honest with you, I am looking at the 2008 CR survey right now and
2003 Camrys are the same as 2002 and 2004.
With no breakdown of what those problems are.
None if you are dealing with Toyota or Honda. If you look at GM,
Chrysler, Mercedes, Kia, Nissan, Ford and VW, there is a wide
selection of models to choose from.
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