Nope. I'm looking for 538's predictions. You cannot go from the raw data they used back to how they interpreted it.
- Web: https://projects.fivethirtyeight.com/2018-midterm-election-f...
- JSON: https://projects.fivethirtyeight.com/2018-midterm-election-f...
You are correct they do not publish the exact math of the forecasts, but you can see how the forecast changed over time.
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.