I had an interesting conversation with a family member this weekend. This person is in an older category range--to 65 year olds nearing retirement. He happens to watch a few reality shows, one of which is "Dancing with the Stars", and we got onto the topic of judging on all of the shows with the "American Idol" format of judging.

From what we could gather, there seems to be 3 formats of judging:

• The public call in and online vote method--used on American Idol
• The expert judge method--used on Project Runway
• The split judge/public vote method--used on Dancing with the Stars
• The peer system where winners vote off another player--used on Survivor

The pure judge only option is not without controversy, as many who watched the 2nd season of Project Runway will attest to. Quality is a subjective thing to measure. The judges + call in vote system seems to be the one that tries to prevent the popularity of a public vote from being a way to game the system, and ensures that actual quality of performance has something to do with the outcome.

There might be others that I'm not aware of. These seem to be the most popular. Let me know if you are aware of others used on these reality shows.

Compare these with the systems used on social software sites.

• For ratings, there's the purely quantitative rating system--used on Netflix
• For comments there's the karma moderation system--used on slashdot and digg to promote or bury posts and comments

What are the methods and typical algorithms for both ratings and comments that prevent gaming these systems?