Hank Lay
retired engineer

He rightly pointed out that the estimates were, at least in part and probably more than "in part" based on flawed data input right at the source… the Emergency Rooms of the hospitals!

When a doctor or whoever clicks on or writes in "table saw" when the perp was a band saw, the resulting data point is useless in a field of data on table saws!

Unfortunately, it seems that people are more interested in a battle of "my degree makes me more knowledgeable [hence more credible???] than your degree or experience makes you…"

Rubbish!

CPSC should clean up its own act by working with the medical profession and ER teams to create better descriptions and categories for the healthcare people to use BEFORE extrapolating from available "data." Or add caveats like, "the source data probably is 60% representative of the reality we’re trying to estimate, so take it all with a grain or more of salt…"

And who am I and what’s my qualification for saying this? I’m "Justin Engineer."

In my Home Depot, there is a box-like guard made of laminate covered MDF that completely encloses the blade and is wide enough that you really could not get your hand under the guard if you tried. I am sure a clever monkey could defeat it or remove it, but it would take considerable effort to have a traumatic amputation with that guard in place.

I would prefer to see the data presented with an explicit confidence interval clearly stated in English, such as something like: we can be 90% confident that the number of hospital visits for injuries involving a table saw (in any way) was between xx,xxx and yy,yyy.

The database itself is fascinating. At least one of the sample "table saw" amputations clearly states in the notes that the accident occurred on a band saw, for instance. There are no flesh detecting technologies for bandsaws that I am aware of.

I was also stuck by the age of the patients in the samples that the database showed me. Patients aged 82 and 77 and 76 etc. which makes me think that familiarity and comfort with a tool can be a double-edged sword. Note to self: Don’t get complacent about safety. This also points away from the litigant in the original table saw lawsuit who I believe had zero hours of table saw usage before his accident.

As a country, I think we could have much better bang-for-our-buck by requiring more effective guards, better training, and more safety oriented product materials (as opposed to the current safety warnings that come with power tools which are designed to prevent lawsuits rather than amputations). I would put flesh detecting technology low of my list bang-for-buck mitigation steps.

Thanks for taking a second look. I admit that statistics are beyond my field of expertise, and I accept that the people who can develop something like NEISS do good things. In trying to understand the numbers on the surface, I did some digging into where they came from. While I don’t know how the methodology works, I do know that the limited amount of data on the front end needs to be reliable or the results on the back end aren’t useful.

If you query the NEISS database, you can download the samples and read the ER doctor’s notes for the samples. Many of these are cryptic and unclear, or show that the data going in doesn’t say what is being said about the numbers coming out. If we’re trying to decide if this is a big enough issue for government action, I don’t think we should be counting a fall that lands on a table saw as a table saw accident. And if there aren’t enough accidents in high school shop classes to even register in the projections, I think it’s irresponsible for anyone to say we’re doing this to protect our children.

So far, most of what has been printed and discussed on this subject has been far from factual. I don’t have formal training in journalism either, but I think we need to take a close look at a complicated subject in order to make a decision that does the most good for the most people. Stay tuned, as there is more to come.

If nobody believed the data that comes out of statistics because they thought it was just a form of guessing, which it is definitely not, then we would loose a very powerful tool for examining the world around us. This was my worry.

Also I am just grumpy today. I am looking forward to your future articles, especially ones on the costs as that is definitely a more subjective measure and I am guessing as a woodworker for many years you know a good number of people who have hurt themselves.

Chris, As for my statement that you should be a professional statistician to do statistics: statistics are not just an opinion, they are a formal field of study that uses specific methodologies to come to conclusions. Without an very large amount of knowledge about how to do statistics you lack the ability to do any meaningful analysis. The same would be the same as saying that building "will/will not" stand without being a mechanical engineer. Yes you can "have an opinion" that their math is wrong but you are just flapping your jaw. There are exceptions usually of the form of the rigging crew saying "this beam should probably be 6" to the left, you know where the bolts actually come through the concrete".

Bob

My tablesaw has been in storage for quite a while as it just wasn’t earning the space it occupied in my too-small shop. nonetheless, I am quite discouraged by the continual trend toward protecting people from themselves at the expense of choices. I’ve also noticed a tendency for people who don’t use tablesaws, or have much need for them, to be the ones leading the charge to eliminating them. Never a situation that sits well with me.

Personally, I think the key (as always) is to try to provide education and resources to improve people’s personal safety. However, legislating to the lowest common denominator of caution or education seems to be more and more the strategy du jour in the US.

Personally, I thought it was quite a good writeup Mr Lang.

Yes, please, after I have my mandatory table saw
lessons I will also attend my mandatory training
for statistics as well since only certified
experts are allowed to have any opinion on
statistics.

I am not even sure what Bob Lang said that was so bad. But
the suggestion that he can’t have an opinion because only
certified gurus can tell us what to do or how to think is
repugnant.

Chris

What I do have an opinion on is this: I believe you do the world a great disservice by attacking modern statistical methods in a very public forum simply because you do not like the numbers they generate. From your article you do not have alternate data that indicate the NEISS data is flawed and from your bio on popularwoodworking.com there is no mention of a background in formal statistics. So I see no grounds for you to be able to disagree with the actual numbers.

Resources like NEISS are designed to take what we feel a number should be and replace it with something founded in reality. Such analyses have brought us modern medicine and engineering and we should not reject them because they run counter to our personal feelings.

I respect you greatly as a woodworker and I would much rather hear about how you plan on reacting to these numbers instead of you attacking them and their methodology. Much like a table saw statistics can seem easy to use at first but you can cause great harm trying to use them without training.

I do have to admit that amateur statistical analysis has been a pet peeve of mine for quite a while and usually sets me off. But I thought it should be stated here.

Bob