Kieffer

I just read most of this thread and I thought I would add something based on some of the responses.

I have participated in this for a couple of years now (I think it's been that long). This survey is legit, my e-mail address has never been sold (I keep CLOSE tabs on that), and what this guy is doing is great! I had one screw-up that was entirely my fault (accidentally joined twice), and he was incredibly kind and pro-active in fixing the problem.

We all know about the flaws in Consumer Reports' reliability studies. Another set of data can't hurt anyone.

So, I'll vouch for Mr. Karesh - and thank him for doing this.

keith100

Hi

I have a couple of questions:-

What do you mean by "Successful Visits"?

Most of your surveys seem to have a few histories, followed by a much longer list of "members who didn't respond" Do your stats ignore them, or assume they have no problems?

What is the purpose? This must be a lot of work. Do you intend to sell it to, for example an Extended Warranty Insurer. I may have missed it, but I don't see a privacy statement on your site. Not that I much mind my email being passed on, since Gmail will reroute any crap I subsequently receive to spam, if I tell it to.

But I am curious

Thanks

Keith

mkaresh

A "successful visit" is one where the repair eliminated the problem.

I focus on these right now because it yields the most robust (stable) result--important with a small sample size. If someone had five repair trips for the same problem, that could distort the results with a small sample size. While it would be nice to track how often that happens, I'd want to do it separately.

Also, with a successful visit we can be especially certain that a problem existed, since it was possible to do something to make it go away.

As Kieffer stated, I do not sell email addresses. I am not sure who, if anyone, I will license the data to--I want to avoid conflicts of interest. So far the only revenue I have planned is to offer paying memberships to people who don't want to participate in the surveys, in addition to the current free memberships for those who do participate. But this option is not available yet.

The main reason I'm doing this is I wanted to see it done, and no one I approached (CR and JD Power) wanted to do it. So I did it myself.

keith100

Thank you

mkaresh

You're certainly welcome. I've learned a lot and made quite a few tweaks based on questions like yours.


The next update will be in August. The more participants there are, the more precise the result will be.

Vehicle reliability research

dalazernet

Can I pose a question?

Is it not true that there is a higher percentage of individuals with problems with their cars on these forums than those who are perfectly happy? Don't get me wrong -- there is a fair share of happy campers here, but many people resort to forums for solutions to problems, etc.

By asking people to participate who are on the forums, are you not getting skewed results by essentially asking a higher percentage of individuals that are likely here BECAUSE of problems? You would almost need to hand out "invites to participate" through some negotiations with nearby dealerships of each car type to get a true fair evaluation from a wide user-base. I was a biology major back in the day, so have my fair share of experience with contaminated/skewed data.

Just my .02 - trying to help you out.

mkaresh

This is a potential risk.

I deal with it by only collecting data going forward, and requiring continuous participation. Previous repairs cannot be reported on the main survey, and don't make it into the analysis. No other vehicle reliability survey takes either step.

This seems to do the trick. The first few months I collected data on the C204, no one reported a repair. And even now the great majority of participants have reported no repairs.

Many participants had joined even before buying their C204, with a previous car. Participants report when they buy and sell cars.

We might work more with dealers in the future. In general, over time fewer and fewer participants will come from forums. But forums have been a source for thousands of excellent participants, and the data have been cleaner than even I personally hoped for.

mkaresh

Next update in August.

So far, 74 owners have signed up to participate.

Additional participants always helpful.

Vehicle reliability research

mkaresh

That update soon.

C204 owners have been excellent participants. To join those already helping us provide the most up-to-date reliability information on the C-Class:

Vehicle reliability research

mkaresh

The updated results were recently posted.

The repair rate for the 2008 C-Class is currently very close to the average, about 62 successful repair trips per 100 cars per year. This is up from 42 three months ago. With the next update, in November, we'll see if the car's reliability continues to worsen, or whether the repair rate levels off (or even improves).

Additional participants always helpful.

TrueDelta Vehicle Reliability Survey results

mkaresh

We'll have a updated set of results in November, which should indicate if the repair rate has leveled off or continues to increase.

Additional participants always helpful.

Vehicle reliability research

mkaresh

That update in just a month, with a preview for participants in a week or so.

Additional participants always helpful.

Vehicle reliability research

mkaresh

The updated result for the 2008 C-Class: 59 successful repair trips per 100 cars per year, which is about average for a 2008.

Very good participation by owners of the 2008, but more would be better. We will need more 2009s to provide a result for the new model year.

For the full set of results, and to sign up to help:

TrueDelta Vehicle Reliability Survey results

C300PO

I'm in!

mkaresh

Thanks, I appreciate it.

This month's survey is the last before the February results. Additional participants would be very helpful, especially for the 2009.

Car reliability research

mkaresh

We have updated results, and with 60 repair trips per 100 cars per year the 2008 C-Class remains close to the average and better than other Mercedes models.

A big thanks to everyone who has been helping. We'll have further updates in May, August, and November. With more participants, we could provide more precise information and also include the 2009.

We now have a separate results page for each model that includes the results for competitors. The page for the C-Class:

Mercedes-Benz C-Class reliability comparisons

mkaresh

In a little over a month we'll start previewing the next set of results to participants. Any 2009s here? We especially need more of those involved, to see how the second model year of the C204 compares to the first.

Car reliability research

mkaresh

Close to those results. Continue to especially need more 2009s. 90 2008s signed up, but only 10 2009s...

mkaresh

14 2009s now. Better, but more remain needed to provide results for this model year.

Car reliability research

mkaresh

We have updated results for the C204 C-Class to include owner experiences through March 2009. In terms of successful repair trips per 100 cars per year, the 2008 has a score of 51, which is about average.

A big thanks to everyone who has been helping. We'll have further updates in August and November. With more participants, we could provide more precise information and cover the 2009 as well.

Mercedes-Benz C-Class reliability comparisons

micropower99

mkaresh

Nearly 100 2008s now signed up, but still only 17 2009s. With more of the latter, we could report whether reliability has improved in the second model year.

Car reliability research

mkaresh

Updated results in a couple of weeks for the 2008. A couple of responses short of the bare minimum with the 2009--so additional 2009s would be especially helpful.

Car reliability research

mirage15

Joining with a 09 now...

mkaresh

We have updated results for the W204 C-Class to include owner experiences through June 2009. In terms of successful repair trips per 100 cars per year, the 2008 has a score of 51, which is about average.

Everyone who has been helping, I certainly appreciate it. We'll have further updates in November and February. With more participants, we could provide more precise information and cover all model years. Especially need more 2009s and (once they're available) 2010s.

Mercedes-Benz C-Class reliability comparisons