4 ms·

It is worth noting that 538 doesn't keep a historical record of their predictions, making it difficult to really see how they predict outcomes coming up to a co

It is worth noting that 538 doesn't keep a historical record of their predictions, making it difficult to really see how they predict outcomes coming up to a conclusion. You can only see the latest/final prediction. 538 also predicted lower chances of victory in the weeks and months leading up to that, then adjusted it on election day vanishing away their earlier guesses. This isn't wrong on the face of it, but people infer from the final datapoint to the conclusion later that same day about 538's accuracy. What I am saying is: 538 needs to keep a historical record of their predictions.

wtallis 8y ago
538 published this last week: https://fivethirtyeight.com/features/when-we-say-70-percent-it-really-means-70-percent/ https://fivethirtyeight.com/features/when-we-say-70-percent-...
dandelany 8y ago
Maybe this was true of past elections, but their 2018 house forecast had a “how this forecast has changed” section that showed their historical predictions throughout election season. It’s still visible here: https://projects.fivethirtyeight.com/2018-midterm-election-forecast/house/#change https://projects.fivethirtyeight.com/2018-midterm-election-f...
- dragonwriter 8y ago
  > Maybe this was true of past elections, but their 2018 house forecast had a “how this forecast has changed” section that showed their historical predictions throughout election season. It has not changed. They did this the whole way back when it was an independent blog before the NY Times (later ESPN then ABC News) picked them up.
  - Someone1234 8y ago
    Where are they? Five different posters have claimed this, but zero have been able to link to the historical predictions.
    - dragonwriter 8y ago
      > Where are they? Five different posters have claimed this, but zero have been able to link to the historical predictions. They are literally charted on the page with the current prediction, e.g., for the 2016 Presidential race (which is locked on the last forecast): https://projects.fivethirtyeight.com/2016-election-forecast/ https://projects.fivethirtyeight.com/2016-election-forecast/ , under “How the forecast has changed”, it charts the forecast (by default, the win probability) for the entire time the race was being forecast.
KC8ZKF 8y ago
The 2016 election predictions are still posted. https://projects.fivethirtyeight.com/2016-election-forecast/?ex_cid=2016-forecast https://projects.fivethirtyeight.com/2016-election-forecast/...
- Someone1234 8y ago
  Yes the newest one. Not the historical ones.
  - hencq 8y ago
    Maybe I misunderstand your argument, but doesn't that linked page have a section "How the forecast has changed"[1]? [1] https://projects.fivethirtyeight.com/2016-election-forecast/?ex_cid=2016-forecast#odds https://projects.fivethirtyeight.com/2016-election-forecast/...
dragonwriter 8y ago
> It is worth noting that 538 doesn't keep a historical record of their predictions, making it difficult to really see how they predict outcomes coming up to a conclusion. You can only see the latest/final prediction. It's worth noting that you are completely wrong: not only do they keep such a record, they also provide a handy chart of it on the latest prediction page so you can easily see exactly how the prediction changed over time.
- Someone1234 8y ago
  Where? Go ahead and link to it.
  - tweezy 8y ago
    Hey I don't have a dog in this fight, but I think this is the link you're looking for. https://github.com/fivethirtyeight/checking-our-work-data https://github.com/fivethirtyeight/checking-our-work-data
    - Someone1234 8y ago
      Nope. I'm looking for 538's predictions. You cannot go from the raw data they used back to how they interpreted it.
      - tweezy 8y ago
        Please look at the actual data on the linked page. Each of the csv files on that page has thousands of predictions 538 made going back as far as 2008. This isn't the raw data they used to make the predictions, these are the actual predications that they made. Edit: For example, here are the headers on the file named presidential_elections.csv year,office,state,district,election_date,forecast_date,forecast_type,party,candidate,projected_voteshare,actual_voteshare,probwin,probwin_outcome These are the actual forecasts they made for presidential elections going all the way back to 2008.
      - wilg 8y ago

wtallis 8y ago

538 published this last week: https://fivethirtyeight.com/features/when-we-say-70-percent-it-really-means-70-percent/ https://fivethirtyeight.com/features/when-we-say-70-percent-...

dandelany 8y ago

Maybe this was true of past elections, but their 2018 house forecast had a “how this forecast has changed” section that showed their historical predictions throughout election season. It’s still visible here: https://projects.fivethirtyeight.com/2018-midterm-election-forecast/house/#change https://projects.fivethirtyeight.com/2018-midterm-election-f...

dragonwriter 8y ago
> Maybe this was true of past elections, but their 2018 house forecast had a “how this forecast has changed” section that showed their historical predictions throughout election season. It has not changed. They did this the whole way back when it was an independent blog before the NY Times (later ESPN then ABC News) picked them up.
- Someone1234 8y ago
  Where are they? Five different posters have claimed this, but zero have been able to link to the historical predictions.
  - dragonwriter 8y ago
    > Where are they? Five different posters have claimed this, but zero have been able to link to the historical predictions. They are literally charted on the page with the current prediction, e.g., for the 2016 Presidential race (which is locked on the last forecast): https://projects.fivethirtyeight.com/2016-election-forecast/ https://projects.fivethirtyeight.com/2016-election-forecast/ , under “How the forecast has changed”, it charts the forecast (by default, the win probability) for the entire time the race was being forecast.

KC8ZKF 8y ago

The 2016 election predictions are still posted. https://projects.fivethirtyeight.com/2016-election-forecast/?ex_cid=2016-forecast https://projects.fivethirtyeight.com/2016-election-forecast/...

Someone1234 8y ago
Yes the newest one. Not the historical ones.
- hencq 8y ago
  Maybe I misunderstand your argument, but doesn't that linked page have a section "How the forecast has changed"[1]? [1] https://projects.fivethirtyeight.com/2016-election-forecast/?ex_cid=2016-forecast#odds https://projects.fivethirtyeight.com/2016-election-forecast/...

dragonwriter 8y ago

> It is worth noting that 538 doesn't keep a historical record of their predictions, making it difficult to really see how they predict outcomes coming up to a conclusion. You can only see the latest/final prediction. It's worth noting that you are completely wrong: not only do they keep such a record, they also provide a handy chart of it on the latest prediction page so you can easily see exactly how the prediction changed over time.

Someone1234 8y ago
Where? Go ahead and link to it.
- tweezy 8y ago
  Hey I don't have a dog in this fight, but I think this is the link you're looking for. https://github.com/fivethirtyeight/checking-our-work-data https://github.com/fivethirtyeight/checking-our-work-data
  - Someone1234 8y ago
    Nope. I'm looking for 538's predictions. You cannot go from the raw data they used back to how they interpreted it.
    - tweezy 8y ago
      Please look at the actual data on the linked page. Each of the csv files on that page has thousands of predictions 538 made going back as far as 2008. This isn't the raw data they used to make the predictions, these are the actual predications that they made. Edit: For example, here are the headers on the file named presidential_elections.csv year,office,state,district,election_date,forecast_date,forecast_type,party,candidate,projected_voteshare,actual_voteshare,probwin,probwin_outcome These are the actual forecasts they made for presidential elections going all the way back to 2008.
    - wilg 8y ago