# What is the difference between a late and exit poll?

When glancing at the Polish presidential elections last Sunday, I saw that the results after the closure of the voting offices (21:00) were tagged as being "late poll" results, with an uncertainty of ~2%.

Then at midnight, a new set of results, called "exit polls", were provided, with an uncertainty of ~1%.

Both seem to come from polls done during the day (and not after 21:00) so I do not understand why they would yield different results.

This is certainly not a matter of logistics: results with information on the person asked (for the representativeness of the sample) can be sent real time to a centralized system, and even if they needed say an hour to gather them, the voters between 20:00 and 21:00 are not likely to introduce such a biais.

How are they different?

• I think you mean 'poll', not 'pool'. If so, maybe edit your question. // A poll with about $2500$ subjects has a margin of error of about $\pm 2\%$ if the proportion being estimated is not too far from $50\%.$ Exit polls are regarded as more accurate because you know the subject being interviewed (a) really did just finish voting (b) for the person stated with no time lag for change of mind. So it's like getting info directly from the population. Also, using historical records from that particular polling place helps to give early warning of unexpected shifts of opinion from prior elections. – BruceET Jul 15 at 1:59
• @BruceET: thanks for the typo, I was influenced by the tag name. Now, I infer from your comment that the "late polls" are not done on the day of the elections? This was not the explanation I saw (where both seemed to happen on the same day). If this is just a poll of the populations shortly before (and possibly during) the elections then I understand where the difference can come from. The fact that the exit polls are not used right after the voting ends (the dramatized apparition of the winner) is something I do not understand, though. – WoJ Jul 15 at 7:18
• In the US, TV networks often have a good idea from exit polls early on election day who will win, But by agreement none of this info is released until all voting is done in a state. This is to avoid premature broadcasting of info that might effect voter turnout or choices. – BruceET Jul 15 at 8:12