2018 House Election: Dems needed a 5.6% popular vote margin to win the House

Richard Charnin
Jan. 20, 2019

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Nate Silver calculated that the Dems needed a 5.6% popular vote margin to win the House (218-217). https://projects.fivethirtyeight.com/2018-midterm-election-forecast/house/

The Dems won by 8% (53.1-45.1%, 8.9 million recorded votes) a 235-200 seat margin. 

But the Dems won 32 of 38 tossups- a 1 in 100,000 probability, an indicator of fraud. Thirty-three of the 38 tossups were held by Repubs. https://richardcharnin.wordpress.com/2018/11/11/2018-house-probability-analysis-indicates-fraud/

Rasmussen was the only pollster to project a Repub win: 46-45%.  https://www.realclearpolitics.com/epolls/other/2018_generic_congressional_vote-6185.html

The National Generic Exit Poll was forced to closely match the recorded vote. https://docs.google.com/spreadsheets/d/1nB_kFzxGOEDQoNU6X1x7YyG6Mc3-Tb1S1r8TjmamwqQ/edit#gid=210218497

2018 NEP	Party ID	Republicans	Democrats	Other
Republicans	33%	94%	6%	0
Democrats	37%	4%	95%	1%
Independents	30%	42%	54%	4%
Calc share	100%	45.10%	53.33%	1.57%
Calc vote	111,478,885	50,276,977	59,451,689	1,750,218
Popular vote	111,835,736	50,449,312	59,379,804	2,006,620
Popular share	100%	45.10%	53.10%	1.80%
	House	201	234

Assuming Silver’s analysis,  a Dem popular vote margin under 5.6% would result in the Repubs winning the House. For example, if the Repubs had 47% of Independents, keeping other NEP percentages constant, the  Dems would have a 51.8-46.6% win (5.2% margin, 5.6 million votes) but the Repubs would win the House.

Generic	Party-ID	Rep	Dem	Other
Rep	33%	94%	6%	0%
Dem	37%	4%	95%	1%
Ind	30%	47%	49%	4%
	Share	46.60%	51.83%	1.57%
	Votes	51,408	57,177	1,732

A 1% gain/loss in margin results in a gain/loss of approximately 7 seats =17/2.6. (17=235-218; 2.6= 8.2-5.6)

Dem Margin	Dem Seats
8.23%	235
7.36%	230
6.49%	225
5.63%	218
4.78%	215
3.93%	210
3.09%	205