The types of irregularities and their occurrence at different stages of the electoral cycle may raise different challenges in terms of proof of an influence on the election result. For some irregularities during the voting and counting process, it is often possible to determine the probable impact on the election result of the affected constituencies if the number of affected votes is known, or by comparing the election result in other comparable polling stations and constituencies without such irregularities. Examples of irregularities where the probable impact on the election result can be determined objectively include double voting or counting, lost ballots or votes, lack of ballot papers for a specific party or candidate, invalid ballot papers, and incorrect invalidation of votes.