I haven't read it but the methodology of the study involved is available here:

https://drive.google.com/file/d/0B3bg_SJKE9GOenpaekZ4eXRBWk0...

Seems to be based on sentiment analysis of about 900k tweets. From skimming:

> Five percent of all tweets mentioning Diane Abbott, @HackneyAbbott, are classified as abusive (8121 out of 140057).