Planes are not safer than cars

[pacoperez]

No amount of possible data collection and analysis will prove whether one mode of transport is safer than the other and, frankly, a more useful question would be: why waste a life trying to prove it anyway?

Thanks HB for a so interesting post. In answer to your question I will tell you: “Because we, the human being, love to know”. This is only a philosophical answer, I can figure out that it should be companies out there who can use this knowledge for any profitable goal.

And definitely, there are companies working as data collectors for statistical purposes, mainly for publicity goals, market frame definition for specific products, etc. I’m sure that if you pay to obtain how many hours people spend driving cars, which cars, which roads, flying, routes and aircraft models you could rigorously study the subject of this thread.

[Gabriel]

Yes, yes, Gabriel & Syd, I do agree with both of you that 600 hours is not enough population of data to evaluate the safety for ALL planes. Correct. But it’s enough data to evaluate the safety for planes in my life.

The problem is not that the number of hours are too small, but that the number of accidents is too small.

If you have 1 accident in the next hour of flight your rate jumps from 0 to 1.7 per 1000 hours (more that triple your rate in cars with 6000 hours of data). If you survive the accident and fly again, and the next flight is not an accident, then the added say 5 hours of "safe" flight will not move the 1.7 an inch (because 1/601 is much more than 0/600 but almot the same than 1/605).

What I tried to do it’s to illustrate with an example a very simple but valid concept: “You can be injured by a machine ONLY if you are using it”. Then the “time of use” matters, not the distance travelled or the free time after. The distance it’s only a consequence of the time. All machines in the world, even the human being : ) has a life time.

I disagree. I agree that usage is important, but usage can be measured in time, distance, cycles, etc...

If you want to evaluate the relative risk of doing a given trip by car or by plane (where it's doable, home to downtown or NY to Tokio are not good examples), it would be unfair to call the plane less safe just because it has a higher accidents-per-1000-hours rate (if that was the case), simply because you will spend at least 5 times less time in the plane than in the car and then your exposure to the risk is 5 times lower and then the chances for the risk to materilize are fewer.

[Gabriel]

I think it was Oscar Wilde who once said....

"There are lies..damn lies..........and statistics !"

Never was a truer word spoken.

Except, maybe, some word spoken about lawyers.

[Highkeas]

................
"There are lies..damn lies..........and statistics !"
..................

Of course there are two types of statistics; one covers births, deaths, etc, and the other is mathematical.

If you think mathematical statistics are lies then do not fly on any late generation aircraft.
Many structural parts are now designed using probablistics rather than deterministics (safety factors). As I write this I'm trying to figure out how to use a probabilistics to design a component.

And if you read MIL-HDBK-5 you will that its metal properties are determined by statistical test and analysis.

[HB-IHC]

Thanks HB for a so interesting post. In answer to your question I will tell you: “Because we, the human being, love to know”. This is only a philosophical answer, I can figure out that it should be companies out there who can use this knowledge for any profitable goal.

And definitely, there are companies working as data collectors for statistical purposes, mainly for publicity goals, market frame definition for specific products, etc. I’m sure that if you pay to obtain how many hours people spend driving cars, which cars, which roads, flying, routes and aircraft models you could rigorously study the subject of this thread.

You're welcome paco...

... but I think you misread my post. The question you "answered" wasn't a question being set, it was a conclusion which recognises that, amongst other numerous and obvious major differences between the two things being compared, cars don't fly and people don't drive up the High Street in an aircraft.

I would therefore suggest that researching a question such as: "are Boeing aircraft safer than Airbus aircraft?", would be a more suitable, relevant and worthwhile piece of research which could, at least, have more of a chance of providing some sort of useful insights, albeit nothing conclusive.

After all: "my data and analysis suggests that..." is as far as anyone can ever say about the data collection - statistical analysis process, and that does not equate to "fact", "truth" or "objective knowledge".

As Oscar Wilde said...

[guamainiac]

Hylcon, one must be able to discriminate on a regional basis and ascertain the usage of the word gonna' and note please that I used an apostrophe which is certainly more acceptable. Some bucolic scholars however will argue this point.

In essence it is a word that denotes an event in the future tense and some examples would be:

I' gonna' kick his butt.

I'm a gonna' go downa' road and gets me sumpin' ta' eat. Wanna come?

In more formal Americanized style it takes the place of "I am going to".

Listen with care to distinguish other similar sounding utterances that will confuse the untrained ear:

I'm a goin' on downa' road ta gets a beer. Wanna come wid me?

Whad' he talkin' bout? He talkin aboud me?

[guamainiac]

The danger in statistics is that they are often extracted and then applied to well, something other that what had originally been the intent of the study. It is apparent that any relationships that have been extracted and the inferences made are subject to question.

So, then we weasel word the hypothesis/null hypothesis by getting a bigger hammer to make the words fit.

US Census wanted "the numbers" of a typical levels of education in US urban minority populations. They maintained, after extensive interviews and the examination of records, that minority individuals in urban areas, greater that 50% had completed at least a high school education.

My own work, that had also been examining some of these numbers was significantly off. My figures were indicated that the graduation rate among these students was 10% to 12%. How could this be?

I had to track it down and learned that the US Census folks limited their studies to areas that bordered military posts. Of course, this is where the young GI's lived and the pressure, if you don't already have a High School Diploma is to get that GED. That in addition to the kids taking advantage of the outreach programs that many Community and State schools that do extension outreach on base, drives that number way up.

I have been asked by seemingly innocent sounding groups with soothing names to rig studies. It is tough in these times to turn down large grants that would fund positions for several years. But when you accept, they just want to change a few little details ... like the selection for study protocols and ... know when to fold em, know when to run.

The word whore comes to mind.

[pacoperez]

After all: "my data and analysis suggests that..." is as far as anyone can ever say about the data collection - statistical analysis process, and that does not equate to "fact", "truth" or "objective knowledge".

As Oscar Wilde said...

It's the end... I do agree : )