We then compute the recall at different values of k. While this is a straight-forward measure to assess the overall quality of different top-k lists, it is not tailored to suit our specific task of response completion.
this measure (a) does not distinguish between (typing) savings for a short word versus a long one, and (b) does not distinguish between the correct answer being higher up in the list versus lower as long as the word is present in the top-k list.