Why are Iowa party assemblies important?

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The Latino vote in party assemblies in Iowa 6:55

(CNN) - The Iowa Democratic Committees are only a few hours away and with them, the true beginning of the 2020 elections.

But what can a single state with a relatively small number of delegates at play tell us about the rest of the primary season? If history is a guide, Iowa assemblies really matter.

The winner of the Iowa assemblies on the Democratic side has often become the Democratic candidate. Since 1972, there have been nine primary seasons without a functioning Democratic president. Six of nine times (67%), the winner of Iowa was also the Democratic candidate. One of those who did not win in Iowa was Tom Harkin, who was a native of the state.

• READ: What you should know about partisan assemblies of Iowa
• Watch in this video: Democrats prepare for the crucial debate hoping to win in Iowa

The success rate of Iowa winners decreases, if you expand it to also include Republican party committees. Including those, nine of the 16 (56%) winners of the Iowa assemblies won the nomination of their party.

Remember, there have been more than 100 candidates who have participated in the committees since 1972. So, an indicator that tells us who is the winner more than half of the time is really an added value.

A closer look at the polls indicates that Iowa not only correlates with success. It is likely to cause that success both in the next competition (the New Hampshire primary) and nationwide.

The winners of the Iowa party assemblies have climbed a median of three percentage points in the New Hampshire primary polls after their victory. In addition, higher expectations (i.e. surveys) in Iowa seem to have an additional effect. For every point that candidates exceed their Iowa polls, they get a 0.5 point rebound in the New Hampshire polls. Candidates who perform poorly in their Iowa surveys see that their New Hampshire survey number deflates by 0.5 points for each point that underestimate their New Hampshire surveys.

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• Watch in this video: Iowa, a key state for the US electoral process. (2019)

The effects at the national level are even greater. As I noted last week, Iowa winners get a seven-point rebound in national median polls. For each point that candidates pass their Iowa surveys, they gain an increase of 0.7 points in their national surveys.

The last Democratic primary that was so full of candidates like this one in 2020 demonstrates the power of Iowa. Democrat John Kerry came from nowhere and won Iowa in 2004. By winning and overcoming his polls in Iowa, Kerry saw a double-digit rebound in their New Hampshire numbers and national surveys. I would have easily won both.

Now, it is very possible that the effect of Iowa this year will be silenced. Iowa is not racially representative of the national primary electorate. In fact, it is not close. The likely electorate of the Iowa Democratic committees is approximately 30 points whiter than the primary electorate potential across the country. Since Democrat Joe Biden is much better among black voters, he could recover from an Iowa loss.

Still, that is a dangerous proposal for him. When Democrat Barack Obama won Iowa in 2008, he won tremendously with black voters.

The important thing about this is that winning (or losing) the partisan assemblies of Iowa is very important. Winning Iowa does not make sure that a candidate wins the nomination, but it certainly helps.

Iowa Partisan AssembliesElections 2020 United States