I'm constantly fighting with my touchpad. It keeps randomly interpreting two-finger taps (which I have set to middle click) while I'm attempting to type. This appears to be due to the touchpad's large size catching my left palm during typing. This is further aggravated by middle click doubling as a paste shortcut in Ubuntu's clipboard app, making typing even more difficult.
Following another answer, I found a command that supposedly changes the dead zone of the touchpad, but it seems to behave strangely: Touches started outside of this region continue to work within this dead zone. Middle clicks with one finger in this dead zone still register.
The command I've tried is
synclient AreaLeftEdge=x, where x seems to be about 1/3rd of the width of the touchpad.
Disclaimer: I wanted to add a comment to an answer here, but silly reputation restrictions makes that impossible.