# GuildWiki

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## No Drops Calculation

This calculates the maximum expected drop rate based on how many tries were made without a single drop occurring.
This is used to calculate the upper bound in probability... eg: if I've opened 5 widgets and got nothing, the rate will probably be under 50%. if I open up 1000 widgets and got nothing, the rate will probably be under 1%. This uses a formula to derive just how high the rate could possibly go and returns that number, rounded to 4 places. It basically takes the standard 'odds I get a drop' formula of Odds=Rate^Tries and solves it for Rate, using 'margin' in place of odds.

In the case of an 'all drops' scenario, invert the result (subtract the result from 100).

Usage: {{Template:DropRates/NoDrop|tries=5|margin=.95}}
tries = the number of attempts at a drop.
margin = the error margin to use. Defaults to 0.95, which equates to 95%

The result is rounded to 4 places of precision, which may display as fewer if the last digit(s) are zeros. The result may be subtraced from 100 for the 'all drops' scenario.

Some samples:
5 tries, no drops 95% margin is ~45%, calculates: 45.07%
50 tries, no drops 95% margin is ~5.8%, calculates: 5.816%
1000 tries, no drops 95% margin is ~0.3%, calculates: 0.2991%
8 tries, 8 drops 95% margin is ~69%, calculates: 68.77%