"Perform surgery" or "carry out surgery"? Photo by Austin Samaritans via Flickr [CC BY-SA 2.O] What kind of collocations are most mistake-prone: strong (e.g. honk the horn, s hrug shoulders ), medium-strong (e.g. wage a war, fail a test ), medium-weak (e.g. perform an experiment, reach a compromise ) or weak (e.g. see a film, read the newspaper )? In the previous post in the series (see HERE ), I looked at some studies focusing on collocational errors across different levels of proficiency and what causes them. One of the studies I cited was by Nadja Nesselhauf (I think it was her doctoral thesis). The study is also interesting in that she tried to pinpoint which collocations are more problematic for learners. But first of all, What counts as a collocation? Learners often have problems with collocations, but what kind of collocations cause more difficulty? On the one hand, there are idioms, such as foam at the mouth , which are technically collocation...