Distributing bulk prizes by percentage lets you determine the chance of winning, as each prize can be won by a specific percentage of players.
This prize setup may seem straightforward, but please note:
If you have limited prizes, it is possible to run out of prizes.
The prizes are arranged in order, from top to bottom, and the percentages affect each other.
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Running Out of Limited Prizes
Imagine you have 1000 unique discount codes to give away, with a winner probability set at 20%.
At first glance, it may seem logical to expect that these 1000 prizes would be claimed after 5000 players have participated in the game. However, this outcome cannot be guaranteed because the 20% chance of winning applies independently to each game session.
The statistical probability means that, with every play, there is a separate chance of winning, regardless of previous outcomes. Therefore, the actual distribution of prizes depends heavily on the number of participants. As the sample size increases—that is, as more players join—the results will more accurately reflect the set winning percentage.
There are two ways you can workaround this:
Use time distribution to spread your 100 prizes out over the campaign period. Learn more about time-distributed bulk prizes.
Add additional bulk prizes, such as consolation prizes. Learn more about consolation prizes.
Independent probability per play
In games like a Wheel of Fortune or Spin the Bottle the chances of winning a prize (or any outcome) are often based on a fixed probability for each play.
Importantly, each play is independent, meaning the outcome of one play does not affect the outcome of another.
For example: If the probability of winning a prize is 10%, this remains true for every spin, no matter how many spins have occurred or what happened before.
Actual distribution vs. Statistical expectation
Set winning percentage refers to the theoretical probability of winning (e.g., 10%).
However, in small sample sizes (e.g., only 10 participants), the actual outcomes may deviate significantly from this expectation due to randomness.
For instance, it’s possible that no one wins, or multiple people win in a row.
As more participants play (increased sample size), the actual outcome will start to close in on the expected probabilities (percentage set for prize). For example: With 1,000 participants, roughly 10% (or 100 players) should win a prize if the winning probability is 10%.
Impact of Prize Order on Winning Percentages
When prizes are distributed based on a specific sequence within a list, this order affects how winning probabilities are calculated.
For example, if you have two prizes and want a total of 50% of players to win, you might think that assigning a 20% chance for the first prize and a 30% chance for the second prize would achieve this. However, this approach doesn’t account for the sequential impact on the overall winning rates.
Instead, to reach the desired total, you should set the first prize's winning chance to 20% and increase the second prize's chance to 38%.
The adjustment is necessary because the second prize's winning probability applies only to the 80% of players the total players, whom didn’t win the first prize.
By recalculating in this way, you ensure that the combined winning chances align with your intended outcome of 50% overall.
To help you calculate these percentages, use this spreadsheet (make a copy of the template to your own account) to find out what you should enter when setting up your bulk prizes. The video below shows how to use the spreadsheet.
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Note that if you rearrange the order of your bulk prizes, you will have to re-calculate the percentages!
As always, remember to test your prizes before going live.