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geekhack Community => Keyboards => Topic started by: Hakhu on Tue, 06 October 2009, 05:49:36

Title: Medical study?
Post by: Hakhu on Tue, 06 October 2009, 05:49:36

Do you know of any medical surveys or studies that prove the superiority of mechanical switch keyboards or rather the stress put on fingerjoints from using rubber-dome switches?

Thanks ...

Title: Medical study?
Post by: Hakhu on Tue, 06 October 2009, 06:29:20

Or any other studies for that matter, scientific studies, that show the superiority of mechanical switches.
Ergonomic, typing speed, error rate etc.

Title: Medical study?
Post by: Rajagra on Tue, 06 October 2009, 06:59:44

I found this (http://journals.lww.com/joem/Abstract/1997/12000/Computer_Keyboard_Force_and_Upper_Extremity.8.aspx).

Quote

Cases generated significantly higher keyboarding forces than controls, although both groups produced forces well above that required to operate the keyboard (4-5 times activation force). Cases reported higher levels of upper extremity symptoms and discomfort than controls, and these measures were highest after the keyboarding task for both groups. No significant correlation between keyforce and key rate was observed in either group. Results suggest that generation of excessive force while working on a computer keyboard may contribute to the severity of upper extremity symptoms.

Does suggest that the key's activation force is not an issue, but bottoming out hard is a big problem.

And we all know what type of switches demand that you bottom out.

Title: Medical study?
Post by: hyperlinked on Tue, 06 October 2009, 09:53:49

Quote from: Rajagra;123380

I found this (http://journals.lww.com/joem/Abstract/1997/12000/Computer_Keyboard_Force_and_Upper_Extremity.8.aspx).


Does suggest that the key's activation force is not an issue, but bottoming out hard is a big problem.

And we all know what type of switches demand that you bottom out.

Ergonomics is a really messy area of practice. One article, especially just an abstract isn't enough to really cite as evidence. There are a number of problems with that study right from the start. Any study that's using self report of pain, distress, and discomfort as a critical measure for their study is already working from behind as people have very different levels of tolerance of physical discomfort and have very different perceptions of what maximum and minimum pain is. Two people can report that they're in so much pain that they don't know how much longer they can keep doing the task you ask them to do, yet one of them may continue for another hour while the other one stops immediately thereafter. Pain reports are totally unreliable unless they're qualified by other data.

I'm curious what the "Composite Symptom Severity" score is and how it's compiled. I'm not familiar with that assessment tool.

There's also no data about the working envioronments between the cases and controls (at least not in the abstract). They may have all been using rubber domed keyboards or they may all have been using mechanical keyswitches.

The kind of upper extremity symptoms and measurses they used would also be relevant to evaluate the soundness of these findings. If they're using a generalized pool of symptoms, then a study size of 48 is a tiny sample size from which to be drawing any definitive findings from.

There are also numerous studies that suggest the speed of typing may be an event bigger factor in injury risk than any kind of force generated by the typing itself whether from key activation or from bottoming out.