Given a disfluent sentence, modify the sentence to it to its equivalent fluent form, preserving the meaning of the sentence.
One example: Who did the Han Chinese want to help the Khitan no I mean the Mongols fight?
Solution is here: Who did the Han Chinese want to help the Mongols fight?
Explanation: The input initially means Khitan and then changes to Mongols, hence this is correct.

Now, solve this: How is it or rather what is it estimated that about half of all variation in homicide rates can be accounted for by?
Solution:
What is it estimated that about half of all variation in homicide rates can be accounted for by?