When preference voting was adopted in Australia a century ago, voting was voluntary. Voting numbers fell by about 10 per cent in each of the next two federal elections because voters did not like the system. Voting was then made compulsory. Since then the number of smaller single-issue parties has increased substantially. They mostly prefer Labor to the Coalition, and draw preferences from Labor. Explicit preference deals further influence this flow of preferences. A clear example of this bias was the loss of a Liberal seat to an independent in Sydney some years ago. The sitting Liberal candidate had won…