Minimizing Mod-Tap errors

With Mod-Tap one can configure key to act as modifier on hold and send keycode on tap. It is rather useful QMK function that can increase efficiency of keyboard layout, but it also can lead to higher error rate.

Tap-Hold configuration options help to mitigate accidental activation of modifiers and refine their behaviour.

BILATERAL_COMBINATIONS is additional configuration option that restricts scope of modifiers to the opposite side of keyboard. While it's still being worked on by Manna Harbour it's worth looking into character stats to explore available options.

Stats are based on 5 000 featured articles from English wikipedia and for each character show it's frequency and cumulative frequency of follower characters. One way to reduce accidental activation of modifiers is to place all common followers on the same side and shield them with BILATERAL_COMBINATIONS configuration option.

Character frequency and cumulative frequency of followers

Based on those numbers one can identify several characters that are good candidates for dual role keys:

Most of those characters are rarely used and usually end up in inconvenient locations. But there are several layouts that have ; and j in home row:

Layout Home keys and frequency of bilateral bigrams (%)
QFMLWY d s t n a e h ;
3.307 4.269 6.802 2.748 5.473 5.967 0.192 0
QWYRFM d s a t o e i ;
3.24 4.224 2.144 6.447 3.743 5.896 4.391 0
QWKRFY d s a t o e l ;
3.263 4.226 2.102 6.557 3.791 5.863 0.821 0
Orthocarpus d s t f j e a h
3.229 3.802 6.794 1.62 0 5.727 5.394 0.208
QWERTY a s d f j k l ;
3.173 3.66 2.7 1.435 0.025 0.175 1.359 0

Bigrams that involve hand alternation are common cause of accidental modifier activation. When frequency of such bigrams is approaching 0 one can minimize Mod-Tap errors.

In Orthocarpus layout j key is already used as right Shift modifier on hold, in other layouts from table above one can take in use home row ; key.

April 11, 2021. Giorgi Chavchanidze.