Pick up the book "The Elements of Typographic Style" or just read the first chapter. Not sure if that counts as one of those studies that uses poor methodology,

Pick up the book "The Elements of Typographic Style" or just read the first chapter. Not sure if that counts as one of those studies that uses poor methodology, but they generally go with serif for easier reading of long passages, but not much difference with short passages. More importantly, column width, line spacing and justification (depending on columns of course) can also make a huge difference in readability, so its not just the font that's important.