@ Sc0tTy - your analysis is too simplistic. Yes, letter frequency is an important factor in keyboard layout design. Frequent letters should be in easy to reach positions. But, letter frequency is certainly not the only factor. Some other factors are:
- bigram frequencies. A bigram is a combination of two letters. In English the most common bigrams are th he and in. This means that it should be easy to type those combinations. Which means that for instance t and h should not be typed with the same finger. Likewise for he, in and so forth. In Dutch the three most common bigrams are en er de
- alternation (prevention of too long one hand strings). You don't want all frequent letters/ bigrams on one hand and all infrequent on the other hand. On an English layout, the five most common bigrams are th he in er an. If you would put therans on one hand, you would end up with far too much long strings on one hand. There are rats near here, the rest treats ..... and so on, all on one hand. A Dutch layout that puts enratid on one hand would be equally horrible.
- hand and finger load. Usually a 50%/50% hand load is desirable. An ideal finger load would be something like (not counting thumbs, and counting l.pinky-l.ring-l.middle-l.index-r.index-r.middle-r.ring-r.pinky) 9% - 11% - 16%-14% 14%-16%-11%-9% Preferences may differ though, some people want less load on the pinkies (thus more on the rest), others like less load on the index and more on the middle and so on.
- low same finger use; low row jumps, low home jump (bottom row -> top row or vice versa)
