On Monday the polls showed two trends: Ciudadanos was recessing and Podemos was gaining votes. Those trajectories could continue, stop or even revert. But if one assumes that they have continued, our predictions will change.

We can simulate an hypothetical scenario where the vote shares of Podemos and Ciudadanos exchanged: Ciudadanos will have a 17,5% vote share and Podemos a 19%. In this scenario our model prediction will be the following:

Podemos would get around 62 seats and Ciudadanos around 58. That is, Podemos will (probably) get more seats than Ciudadanos, but not in proportion to its votes. This happens because of the territorial distribution of the two parties voters: Ciudadanos has an advantage because they get more votes in small districts, and there the Spanish electoral system makes seats 'cheaper' in votes.

In this scenario Podemos has a 39% chance of being fourth, a 42% of being third, and a 17% of being second. Ciudadanos has chances 50%, 37% and 10%, respectivelly. PSOE will be second with a 70% chance.

The chance of different coalitions will also change in this hypothetical scenario. PP and Ciudadanos will have only a 50% chance of reaching a majority of seats. A left coalition will have a 15% chance, so is still unlikely. A coalition of three with PSOE, Ciudadanos and Podemos will have a 92% chance.

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The results of the next Spanish election are highly uncertain for several reasons. Many voters are undecided, coalitions are unclear, and we have no historical records for the new parties. And besides all this we have volatility: during this last weeks polls –and probably voters– have changed a lot.