Re: Info about DVORAK Keyboard Design

Hi,

Dvorak didn't just take strength and frequency into account.  As others
have mentioned, he wanted to increase hand alternation.  This is why the
vowels are placed on the left hand.  He also wanted to promote typing
from the outside-in, as mentioned, since this is easier than typing from
the inside towards the outer end.

He thus wanted to make the most common digrams easy to type.  TH is the
most common digram in English.  It is typed on the home row in Dvorak. 
Likewise, OU is the most common vowel-vowel digram in English.  This is
probably the reason Dvorak put the U on the left index finger instead of
putting I there.  I is about twice as frequent as U in English, but the
vowel-vowel digrams involving U are about 40% more common than the
vowel-vowel digrams involving I.  Thus Dvorak slightly sacrificed the
concentration of keys in the home keys/home row in order to facilitate
typing the most common digrams.

The frequency of the following U digrams [au ua ou uo eu ue ju uj qu uq]
exceeds the frequency of the following I digrams [ai ia oi io ei ie ji
ij qi iq] by about 40% using a sample of english texts.

In other words, I is more common than U, but I is most often combined
with consonants (which are on the other hand in Dvorak), whereas U is
most often combined with other vowels.  Some people have tried to
"improve" Dvorak by swapping the I and the U, but this is questionable
when one takes into account digrams.

For comparison, a layout like Colemak <http://colemak.com/> has a
slightly higher percentage of keys in the home row than does Dvorak, and
at first sight, appears slightly better than Dvorak.  But, it places H
and U off the home keys, which slows down the typing of the TH and OU
digrams (as well as HE, which is the second most common digram in
English).  There are also other very common digrams involving H, such as
CH, SH, and WH.  Those involving U include QU (question), JU, AU, etc.

Another reason is undoubtedly ease of learning.  Having the left home
row consist of AOEUI facilitates learning.

Another factor that I am not sure Dvorak took into account is finger
length.  The C in Dvorak may be easier to type than the G in Dvorak
because the middle finger is longer than the index finger.  And indeed,
the C is more common in English than is the G.


> > Also please send if you have any links or references that explain the
> > DVORAK
> > process in great detail.
>   

It obvious that Dvorak gave great importance to digrams, as he slightly
sacrificed the placement of the most common letters in order to
facilitate the typing of digrams.  U is much less common than R, but U
is placed in the home row, while the more frequent R is relegated to the
top row.  It is clear that Dvorak's strategy was to place the second
letter of the most common vowel-vowel digrams (U) on the left index
finger, and to place the second letter of the most common
consonant-consonant digrams (H), on the right index finger.

He also tried to reduce the one-finger ratio and to minimize typing on
the bottom row.  For comparison, Colemak has a better one-finger ratio
than Dvorak.  But it places more keystrokes on the bottom row.  This has
the side-effect that there are more hurdles in Colemak than in Dvorak. 
Hurdles are when you have to jump from the bottom to the top row, or
from the top to the bottom row, on one hand.  This is the most
uncomfortable move in touch-typing.  Examples of this are VE in qwerty,
or BR in Dvorak.

Regards.



Yatin Sethi wrote:
>
> Hi Guys,
>
> I am a new member. I wanted some more info regarding the DVORAK
> Keyboard. I
> have read about the design principles given out by DVORAK and
> importance of
> frequencies in laying out the keys. I am getting the following
> questions in
> my mind, please see if you can help me in these:
>
> 1) DVORAK said - "For maximum speed and efficiency, the most common
> letters and digraphs should be on the home row, which is where the
> fingers rest, and under the strongest fingers."
> What does he mean by strongest fingers ??? Is the middle finger the
> strongest, coz he has placed the most common vowel (E) and most common
> consonant (T) under middle fingers ?? Or there is some other reason ??
>
> 2) Why were the vowels kept on LEFT side although the sum of frequencies
> of vowels in Home Row is MORE than sum of consonants in Home Row ??
>
> You guys must have read about this earlier. I hope you would be able
> to help
> me out. Thanks a lot for your consideration.
>
> Also please send if you have any links or references that explain the
> DVORAK
> process in great detail.
>
> Regards'
>
> -- 
> Yatin Sethi
> www.yatinsethi.com
>
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> .... Make use of it "
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