What do you mean by "research into those improvements"? A steno theory is a correspondence between key combinations and output. The theory is a (hopefully) coh

What do you mean by "research into those improvements"? A steno theory is a correspondence between key combinations and output. The theory is a (hopefully) cohesive system for remembering that mapping. By academic research, I don't know of any. I don't know of any for 1:1 keyboard mappings either. I suppose you could say that "used by the entire profession of court reporters daily for a century" might constitue some kind of research. A steno theory can behave more like a language than a layout. It may evolve over time and has an associated culture. But it also operates at the individual level. No two steno users will have the same dictionary.