Caucus Math in 3 minutes

Iowa Democratic Party
3 min readJan 31, 2016

Caucusing is fun, easy and important — and yes, there is math involved! That’s why we’re here — to help you get to the bottom of the math behind the Iowa Democratic Caucuses.

First things first — on Monday, February 1st, Iowa Democrats across the state will gather at nearly 1,700 precincts to make their preferences for the Democratic nomination for President. It’s a pretty big deal.

Presidential candidates are then awarded delegates based on the preference group’s size at each of the precinct locations.

That’s the easy explanation. Let’s dive in a little deeper to understand just exactly how delegates are awarded on caucus night:

Step 1: Precinct chairs count the number of eligible caucus goers.

Step 2: To be awarded delegates, candidates must have a minimum number of caucus attendees in his or her group. This is called viability. Precinct chairs will determine the viability threshold using these formulas:

  • If the caucus elects one delegate: The delegate is elected by a simple majority.
  • If the caucus elects two delegates: Viability is 25%
  • If the caucus elects three delegates: Viability is 16.66%
  • if the caucus elects four or more delegates: Viability is 15% →this is the viability at most of our caucus locations!

Step 3: Caucus goers will then get into preference groups and precinct chairs will ensure all of the groups are viable.

Step 4: If preference groups are not viable, caucus goers in those groups can realign and join a viable group, or pull people from other groups to become viable themselves.

Step 5: Once you are only left with viable groups, now it’s time to award delegates.

Here’s the formula:

(Number of people supporting your candidate) x (Number of total delegates the caucus is electing)

DIVIDED BY

(Total number of people at the caucus)

Quick example: Your precinct elects 5 delegates. 100 people show up to caucus. Here is how people align:

Candidate A — 40 people (40x5/100=2 Delegates)

Candidate B — 35 people (35x5/100=1.75 delegates, round up to 2 Delegates)

Candidate C — 25 people (25x5/100=1.25 delegates, round down to 1 Delegate)

Step 6: Finally, sometimes the math can award too few or too many delegates. Then, here’s what happens:

  • If the total number of delegates is fewer than the number to be elected, an additional delegate is awarded to the group(s) with the highest decimal below 0.5.
  • If the total number of delegates is greater than the number to be elected, a delegate is subtracted from the preference group(s) with the lowest decimal above 0.5 — but a group can’t lose it’s only delegate.

There you have it. You have now learned about Caucus Math!

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Iowa Democratic Party

The Iowa Democratic Party is dedicated to promoting Democratic principles across Iowa & electing qualified and dedicated candidates at all levels of government