I'm interested in what people know about UX regarding horizontal button groups and radio buttons. There seems to be a wealth of stats around when and where to use radio buttons as opposed to select/dropdown lists but I'm curious about how button groups perform.
My assumption is that button groups take up a little less room (vertically) but I have seen data show that forcing the reader to read top to bottom as well as left to right adds effort/fatigue and that keeping everything in a list format is beneficial. Anybody have any strong opinions (or better yet, data) on this?
I don't have data, but, for me, it would come down to a couple of things:
Scalability - button groups aren't particularly scalable as they need to fit horizontally within the available space. If you're likely to have selections that have more than a handful of options, radio buttons would make more sense. Similarly, if the option labels are potentially more than one or two words radio buttons would be my choice.
Style - if the rest of your form elements follow common standards (e.g. checkboxes and dropdowns that look like regular checkboxes and dropdowns) it would make sense to stick with radio buttons.