NFL Parlays Huge Spreads and O/Us 4-0 this weekend

[LogistX]

This is the outcome of blindly betting this in the NFL since 1990 based on the repole numbers. The criterion was where spread >= (1/4)(total). This only counts weeks 1-9 of 2007 and the regular season only for all other years. The 3 numbers are wins-losses-halfwins. A half win is where you win half of the parlay and tie the other half.

<font class="small">Code:</font><hr /><pre>Season Over/Fav Under/Dog
2007 6-7-0 2-10-1
2006 10-27-1 9-28-1
2005 5-19-0 8-16-0
2004 3-13-1 4-13-0
2003 4-15-0 6-13-0
2002 6-16-0 4-18-0
2001 5-16-0 2-17-2
2000 8-20-1 6-22-1
1999 6-20-0 8-17-1
1998 8-18-0 4-22-0
1997 3-17-1 4-16-1
1996 6-16-1 4-19-0
1995 4-21-0 9-16-0
1994 9-15-0 9-15-0
1993 12-31-0 15-28-0
1992 8-44-1 15-38-0
1991 8-23-0 7-24-0
1990 3-20-1 7-17-0
TOTAL 114-358-7 123-349-7
</pre><hr />

Here are the games this year that qualified (weeks 1-9).

2007 Weeks 1-9:
Week 2: Buf(3) +10 @ Pit(26) o/u39 [loss]
Week 2: NJY(13) +10 @ Bal(20) o/u 33 [half]
Week 2: Oak(20) +10 @ Den(23) o/u 37 [win]
Week 2: KC(10) +12 @ Chi(20) o/u 34.5 [win]
Week 3: SF(16) +9.5 @ Pit(37) o/u 38 [win]
Week 3: Buf(7) +16.5 @ NE(38) o/u 41 [win]
Week 4: Stl(7) +13 @ Dal(35) o/u 47 [loss]
Week 4: KC(30) +12 @ Sdg(16) o/u 38.5 [loss]
Week 5: Cle(17) +15.5 @ NE(34) o/u 48 [win]
Week 6: Stl(3) +9 @ Bal(22) o/u 36.5 [loss]
Week 7: NE(49) -15.5 @ Mia(28) o/u 49.5 [win]
Week 8: Was(7) +14.5 @ NE(52) o/u 46.5 [win]
Week 9: Bal(7) +9.5 @ Pit(38) o/u 36 [win]

With standard payouts of +2.6 for a win, -1 for a loss and +0.91 for a half win, it looks like blindly doing this for the NFL is -EV. This year with the New England anomaly it appears to be doing well.

Edit: I was improperly counting half wins where the spread was tied. If under/dog tied, I was not counting this as a loss for over/win.

[Thremp]

Seems std. I draw my cutoffs for parlays higher than 25%.

[brendanb438]

Does raising the cutoff to 33% or greater drastically change the outcome?

Naj I def understand that with your example there isn't anything correlated about that type of parlay. Also I didn't see any threads talking about this this season or last season so sorry for bringing this up.

LogistX thanks for running those numbers. Looks like there isn't any correlation in the NFL like there is in NCAA football. At least not at the 25% threshold.

[LogistX]

[ QUOTE ]
Does raising the cutoff to 33% or greater drastically change the outcome?

[/ QUOTE ]
I'll check when I get home from work. In theory, the higher the %, the better the parlay should be. I suspect that blindly betting will almost always be -EV. However, a look at the historical covariance may be a good thing. If you plan to bet one side anyway (meaning you believe the probability is better than 52.4% at -110), parlaying it may be better.

[LogistX]

Here's the numbers again where spread &gt;= (1/4)(total). I added two extra columns. The extra columns attempt to capture the correlation between the events. "Fav" shows the win/loss/tie record of the over given that the favorite covers. "Dog" shows the win/loss/tie record of the under given that the underdog covers.

<font class="small">Code:</font><hr /><pre>Season Over/Fav Under/Dog Fav Dog
2007 6-7-0 2-10-1 6-2-0 2-2-1
2006 10-27-1 9-28-1 10-6-1 9-11-1
2005 5-19-0 8-16-0 5-5-0 8-6-0
2004 3-13-1 4-13-0 3-2-1 4-7-0
2003 4-15-0 6-13-0 4-5-0 6-4-0
2002 6-16-0 4-18-0 6-5-0 4-7-0
2001 5-16-0 2-17-2 5-6-0 2-6-1
2000 8-20-1 6-22-1 8-8-0 6-5-0
1999 6-20-0 8-17-1 6-5-0 8-6-0
1998 8-18-0 4-22-0 8-5-0 4-9-0
1997 3-17-1 4-16-1 3-5-0 4-7-1
1996 6-16-1 4-19-0 6-6-0 4-6-0
1995 4-21-0 9-16-0 4-3-0 9-9-0
1994 9-15-0 9-15-0 9-3-0 9-3-0
1993 12-31-0 15-28-0 12-7-0 15-9-0
1992 8-44-1 15-38-0 8-9-1 15-20-0
1991 8-23-0 7-24-0 8-8-0 7-8-0
1990 3-20-1 7-17-0 3-9-1 7-4-0
TOTAL 114-358-7 123-349-7 114-99-4 123-129-4
</pre><hr />

Here's the numbers where spread &gt;= (1/3)(total).
<font class="small">Code:</font><hr /><pre>Season Over/Fav Under/Dog Fav Dog
2007 1-1-0 1-1-0 1-0-0 1-0-0
2006 2-5-1 2-6-0 2-0-1 2-3-0
2005 1-6-0 3-4-0 1-1-0 3-2-0
2004 0-2-0 0-2-0 0-1-0 0-1-0
2003 0-3-0 0-3-0 0-2-0 0-1-0
2002 0-3-0 1-2-0 0-1-0 1-1-0
2001 2-3-0 0-3-2 2-0-0 0-1-1
2000 4-6-0 2-8-0 4-3-0 2-1-0
1999 2-6-0 4-4-0 2-2-0 4-0-0
1998 2-3-0 0-5-0 2-1-0 0-2-0
1997 1-5-1 2-5-0 1-3-0 2-0-0
1996 0-4-0 2-2-0 0-0-0 2-2-0
1995 1-7-0 3-5-0 1-1-0 3-3-0
1994 3-6-0 4-5-0 3-1-0 4-1-0
1993 4-10-0 6-8-0 4-2-0 6-2-0
1992 3-24-0 6-21-0 3-7-0 6-11-0
1991 3-11-0 5-9-0 3-4-0 5-2-0
1990 1-10-0 4-7-0 1-3-0 4-3-0
TOTAL 30-115-2 45-100-2 30-32-1 45-36-1
</pre><hr />

Firstly, it definitely looks like the spread being 1/4 of the total is not enough. If the probabilities of the events were 50% and there was no correlation (on average) you would expect about a 1:3 ratio of wins to losses. 237-707-14 is almost exactly that.

When the spread is 1/3 of the total, you start to see something. It looks like the under and the dog may have some correlation. Since even when the favorite covers, the game fails to go over roughly 50%, there does not seem to be much of a correlation between over and favorite here. Anyone want to chime in on statistical significance? Or is this like seeing a pattern where none exists?