Correcting Comma Errors in Learner Essays, and Restoring Commas in Newswire Text

While the field of grammatical error detection has progressed over the past few years, one area of particular difficulty for both native and non-native learners of English, comma placement, has been largely ignored. We present a system for comma error correction in English that achieves an average of 89% precision and 25% recall on two corpora of unedited student essays. This system also achieves state-of-theart performance in the sister task of restoring commas in well-formed text. For both tasks, we show that the use of novel features which encode long-distance information improves upon the more lexically-driven features used in prior work.