Projection Update: Nanos 9/12-14 and Mainstreet 9/11-13

The following polls have been added to the model:
Nanos' 9/12-14 national poll (national results only; current weight among national polls: 21 20%)
Mainstreet's 9/11-13 national poll (QC and partial national results only; current weight among national polls: 26 24%)
For a full list of included polls, see previous Projection posts.
Update Sept. 15: Fixed small spreadsheet issue related to change in age formula at writs issuance.

Note on rolling polls (such as Nanos): Only non-overlapping samples will be used. Thus, this Nanos poll replaces the 9/11-13 one; the latter will be used when the most recent Nanos poll is 9/14-16, 9/17-19, etc. 
Note on Mainstreet poll: National results for NDP and Greens were estimated from QC results and "little change in other provinces."

As the Le Soleil article states, the big news in the Mainstreet poll is the Liberal drop in QC. Has the Liberal momentum in QC reversed because Trudeau wouldn't rule out intervening on the Bill 21 court case in the future? We will, of course, have to wait for more polls to be sure. But Quebecers' vote intentions often shift massively late in the campaign, so this is a reminder of the potential for a bad "October surprise" for the Liberals in QC.

Projection as of the latest national poll (midpoint: September 13)
LIB - 160.4 160.6 (34.6%)

CON - 146.2 146.1 (36.6%)
NDP - 15.8 15.7 (11.7%)
BQ - 11.1 (4.3%)
GRN - 3.5 (9.5%)
IND - 0.5
PPC - 0.4 0.5
If you're new to my 2019 projections, view key interpretive information here.

Seats changing hands since the last projection:
- In QC, CONs retake Jonquière and Trois-Rivières from LIBs.
- In QC, the BQ gets Pierre-Boucher--Les Patriotes--Verchères back from LIBs.
- In ON, LIBs get St. Catharines back from CONs.