Electoral fraud is less common in proportional representation systems than it is in plurality systems

What impact does the electoral system in use have on levels of electoral quality and fraud? Fabrice Lehoucq and Kiril Kolev share research which shows that plurality electoral systems lead to more ballot rigging than do proportional systems, that plurality systems are associated with inferior election quality in the Quality of Elections Database, and that electoral formulae have as much impact as social structure on whether elections are free and fair.