Are prediction markets accurate?
In short
On liquid markets, prices have lined up with outcomes reasonably well: things priced at 70% tend to happen about 70% of the time. They go wrong on thin markets, on long shots (which tend to be overpriced) and when news arrives faster than trading.
Why they tend to work
Traders who are wrong lose money and traders who are right make it, so prices get pulled toward the best available information. Many people with different information add up to one number.
Where they fail
Thin markets can be pushed by one trader. Long shots tend to be overpriced, because people like cheap tickets. Long-dated markets also tie up money, which can bend the price.
What that means for PredictRips packs
Long-shot cards return less than favorites on average for exactly this reason. Pack value at open is about 90% of the price; held to the result, about 89% on average.