Data collected from PredictWise on September 8, 2016

On this date, all but 10 states had market probabilities on the PredictWise website above 90 percent or below 10 percent. These states can be ignored. The 10 states, ranked by market probabilities for the Democratic candidate, are:
state prob votes sumvotes
PA 90 20 269
NH 87 4 273 pivot
NV 74 6
FL 70 29
OH 63 18
NC 61 15
IA 55 6
AZ 19 11
GA 15 16
MO 12 10
75 = PredictWise market-based probability that Clinton wins the presidential election.

"sumvotes" is the sum of the electoral votes of all the states ranked above the state plus the state's vote. 270 votes are needed to win. You can see that New Hampshire is the pivot state. If Clinton takes New Hampshire and all the states ranked above it, she gets 273 votes. Of the states ranked below New Hampshire, she could also win by not taking New Hampshire but taking any one of the others. This would, of course, violate the ranking assumption.

There is evidence that traders are not quite using the ranking assumption. According to the ranking assumption, the probability that Clinton wins overall is the probability that she wins the pivot state, New Hampshire, which is 87. On the PredictWise website, the market-based probability that Clinton wins the presidential election (in the electoral college) is 75, somewhat below 87.

Table 1 gives more details.

Data collected from PredictWise on September 20, 2016

On this date, all but 16 states had market probabilities on the PredictWise website above 90 percent or below 10 percent. These states can be ignored. The 16 states, ranked by market probabilities for the Democratic candidate, are:

state prob votes sumvotes
MN 89 10 192
NM 88 5 197
VA 88 13 210
ME 87 4 214
MI 84 16 230
WI 84 10 240
PA 84 20 260
CO 82 9 269
NH 81 4 273 pivot
NV 61 6
FL 59 29
NC 53 15
OH 51 18
IA 41 6
AZ 12 11
GA 12 16
72 = PredictWise market-based probability that Clinton wins the presidential election.

"sumvotes" is the sum of the electoral votes of all the states ranked above the state plus the state's vote. 270 votes are needed to win. You can see that New Hampshire is the pivot state. If Clinton takes New Hampshire and all the states ranked above it, she gets 273 votes. Of the states ranked below New Hampshire, she could also win by not taking New Hampshire but taking any one of the others. This would, of course, violate the ranking assumption.

There is evidence that traders are not quite using the ranking assumption. According to the ranking assumption, the probability that Clinton wins overall is the probability that she wins the pivot state, New Hampshire, which is 81. On the PredictWise website, the market-based probability that Clinton wins the presidential election (in the electoral college) is 72, somewhat below 81.

Table 1 gives more details.

Data collected from PredictWise on October 4, 2016

On this date, all but 8 states had market probabilities on the PredictWise website above 90 percent or below 10 percent. These states can be ignored. The 8 states, ranked by market probabilities for the Democratic candidate, are:

state prob votes sumvotes
MI 90 16 273 pivot
FL 76 29
NV 75 6
NC 64 15
OH 45 18
IA 37 6
AZ 17 11
GA 11 16
80 = PredictWise market-based probability that Clinton wins the presidential election.

"sumvotes" is the sum of the electoral votes of all the states ranked above the state plus the state's vote. 270 votes are needed to win. Michigan is the pivot state, with a probablility of 90. All the states above Michigan in the ranking have probabilities greater than 90 (they are not listed above). If Clinton takes Michigan and all the states ranked above it, she gets 273 votes. Of the states ranked below Michigan, she could also win by not taking Michigan but taking Florida or North Carolina or Ohio. This would, of course, violate the ranking assumption.

There is evidence that traders are not using the ranking assumption. According to the ranking assumption, the probability that Clinton wins overall is the probability that she wins the pivot state, Michigan, which is 90. On the PredictWise website, the market-based probability that Clinton wins the presidential election (in the electoral college) is only 80.

Table 1 gives more details.

Data collected from PredictWise on October 25, 2016

On this date, all but 9 states had market probabilities on the PredictWise website above 94 percent or below 10 percent. These states can be ignored. The 9 states, ranked by market probabilities for the Democratic candidate, are:

state prob votes sumvotes
PA 94 20 273 pivot
NV 92 6
FL 86 29
NC 82 15
OH 61 18
AZ 55 11
IA 51 6
GA 20 16
AL 11 3
90 = PredictWise market-based probability that Clinton wins the presidential election.

"sumvotes" is the sum of the electoral votes of all the states ranked above the state plus the state's vote. 270 votes are needed to win. Pennsylvania is the pivot state, with a probablility of 94. All the states above Pennsylvania in the ranking have probabilities greater than 94 (they are not listed above). If Clinton takes Pennsylvania and all the states ranked above it, she gets 273 votes. Of the states ranked below Pennslyvania, she could also win by not taking Pennslyvania but taking, say, Florida. This would, of course, violate the ranking assumption.

There is evidence that traders are not quit using the ranking assumption. According to the ranking assumption, the probability that Clinton wins overall is the probability that she wins the pivot state, Pennslyvania, which is 94. On the PredictWise website, the market-based probability that Clinton wins the presidential election (in the electoral college) is 90, slightly below 94.

Table 1 gives more details.