Final answer:
Small parties in a single-member district plurality system are more likely to win seats in systems that offer proportional representation or majoritarian voting with run-offs, as these systems can either allocate seats based on the share of votes or require a candidate to achieve a majority to win.
Step-by-step explanation:
Small parties in a single-member district plurality system are more likely to win seats when they can avoid the winner-take-all dynamic and participate in systems that allow for proportional representation, where legislative seats are allocated based on the total share of votes they receive. In plurality voting, it is much harder for small parties to win as the candidate with the most votes wins, regardless of whether it's a majority. This often dissuades voters from supporting smaller parties due to the fear of 'wasting' their votes on candidates unlikely to win. Systems that utilize proportionality, on the other hand, can include mixed systems where a portion of the seats in a legislature are filled using proportional representation to balance out distortions from plurality voting. Abandoning plurality voting or switching to a majoritarian voting scheme with run-off elections also increases the potential for small party success, as a candidate must secure a majority to win.