Preference voting is not the most commonly used form of voting in the United States. Even so, it is very interesting and has its place in our society. This lesson reviews preference ballots and schedules.
Introduction to Preference Ballots
When was the last time you voted? Was it something really important, like a presidential election, or something less serious, like voting on the theme for an office party? In the US, most governmental elections use a form of voting where a voter selects their single choice from the options and does not indicate any further information about the other candidates. The only option is to give your first choice and nothing else.
But, for the less formal voting, like voting on the theme of an office party, more information than simply a person's first choice may be desired. Preference ballots allow voters to rank all the available options in order of preference. In this lesson, we will review preference ballots and preference schedules (the results of preference ballot voting.)
Example of Preference Voting
A great place to find preference voting is in an office when the boss wants the employees to make a decision about something that will affect them personally. Let's consider the scenario that an office with 100 employees is asked to take a vote on a theme for the upcoming office party. Instead of doing a majority rules vote, where the option that gets more than 50% of the votes wins, the boss wants to get an idea of how people feel about each of the options. So, a preference ballot would be developed that asks the employees to rank the options in order of their own preferences.
Using this ballot, a voter can not only indicate which option they like best, but also which they like least and everything in between. Because everyone can rank the options in whatever order they choose, it is easy to see that there are many possible combinations that could result from this form of voting.
The multiple outcomes lead us to a preference schedule, which is just a table of the results from the preference ballot. Above is a possible preference schedule for our office party.
You can see that having no theme at all is not an overly popular idea with quite a lot of the group (66 out of 100 would rather have some theme rather than no theme). You can also see that having something in the range of a snow theme is the least unpalatable to the employees.
You can deduce this from the fact that none of the result combinations show the snow theme as last in the rankings. So, it is clear that the preference schedule really does give much more information about the voter's opinions than a more traditional 'pick your favorite option' style vote.
How to Determine a Winner
With so much more information, it can be tricky to determine a winner in a preference ballot election. There are actually many different models used to determine a winner. Each of these is discussed in detail in other lessons. In summary, a winner can be determined by:
- Plurality, the option with the most first place votes
- Use of the Borda method to assign values to each place ranking
- Use of plurality with elimination, or automatic run-off, until one option obtains a majority
It is up to the organizer of the election to pre-determine what method will be used to determine the final result.
Rules for Preference Ballots
Even though there are many different ways to determine a winner in a preference ballot, there are some rules that apply to all preference voting. A preference ballot does not allow two options to be ranked on the same level. This is called a linear ballot because selection choices must move in a line from one to the next, never plateauing at the same rank.
In this way, preference ballots are transitive, meaning that if option A is preferred by a voter over option B, and option B is preferred over option C, then A is automatically preferred over C. Basically, in our office party vote, if a person ranks Hawaiian over snow and snow over no theme, then it is assumed they would also rank Hawaiian over no theme.
Another interesting rule for preference ballots is that relative preferences of an individual voter cannot change if one or more options is eliminated. In our example, let's say that Sally voted in this order: Hawaii, snow, '80s music, no theme. Now, the boss has decided that snow is definitely out of the question. Sally's relative preferences will not change with this alteration to the overall choices; her ballot will still indicate that she prefers Hawaii over '80s music over no theme at all.
This has been a very quick review of preference ballots (a voting style that allows voters to rank order all of the options in a vote). Preference ballots lead to preference schedules, which indicate how many votes each possible outcome received.
We learned that there are many different methods to determine the winner of a preference vote, including the Borda method, plurality with elimination and, simply, plurality. We also saw that there are a few rules that apply to all preference ballot voting. The rules are that the voting must be linear, transitive and relative preferences can't be impacted by the elimination of options.
Thanks for joining me today. I hope you've enjoyed it. Bye!
After watching this lesson, you should be able to:
- Define preference ballots and preference schedules
- Explain the three methods of determining a winner in preference voting
- Describe the rules of preference voting