There is a reasonable chance that this presidential race will be decided by who wins Pennsylvania. I think Trump is more likely than Clinton to win. Here’s why:

The RCP average has Trump down by six points in Pennsylvania. This average is based on six polls, five of which give us data broken down by party ID. These five polls are assuming that 48% of 2016 Pennsylvanian voters will be Democrats and 40% will be republicans.

In 2008, 37% of Pennsylvanian voters were Republican and 45% were Democrats. In 2012, 35% were Republicans and 45% were Democrats. Thus, pollsters are assuming that both republicans and democrats will see an increase in turnout this year which will lead to the biggest +D bias in turnout seen since before Obama. This is a very bad assumption.

First of all, in terms of voter registration in Pennsylvania, the pro-democrat bias today is significantly smaller than it was in 2008 or 2012. Since 2012, Pennsylvanian democrats have lost sixty-four thousand members. In that same time span, Pennsylvania Republicans gained one hundred and sixty-three thousand members. This should lead us to expect a more “pro republican” composition of voters in 2016.

Moreover, the pollsters are assuming that there will be a record low level of independent turnout this year in Pennsylvania even though the absolute number of people registered in the two major party has fallen since 2008.

This should lead us to expect a more “pro republican”and “pro-independent” composition of voters in 2016, and both changes should benefit Trump.

Secondly, democrat primary turnout in Pennsylvania was down 31% in 2016 compared to 2008. Republican turnout, by contrast, increased massively (+88%) and hit an all-time record in the state.

Since primary turnout correlates with final election turnout, this data should lead us to expect that democrats will have better turnout than they did in the pre-Obama years but won’t relive Obama’s record numbers. Republicans, by contrast, will likely see much higher turnout than they ever have before.

Furthermore, in spite of having a closed primary, Pennsylvania’s 2016 primary turnout was roughly 60% as large as their 2012 general election turnout. Given this, it is ludicrous to think that this change in primary turnout won’t predict a change in general election turnout.

Thirdly, all over the country, African American turnout has been lower than usual in early voting. Democrats lost the White vote in Pennsylvania in 2012 and in 2008. Thus, African American turnout is a key element of total voter turnout for democrats in Pennsylvania and there is reason to think that it will be down this year.

Given all this, expecting 2016 voter turnout in Pennsylvania to be better for democrats than it was in 2008 or 2012 is just not realistic. The data clearly suggests that we should expect democrat turnout to fall relative to 2008 and republican/independent turnout to increase. In fact, we should expect the best republican performance in Pennsylvania at least since Bush senior ran in 1988.

Some people don’t feel comfortable criticizing real clear politic’s pollster averages. If you are such a person, consider this: RCP under predicted Trump’s margin of victory in the Pennsylvania primary, which occurred before Cruz dropped out, by 14 points. Thus, for them to be within 6 points of the final vote in the general election pollsters will need to be more than twice as accurate as they were in Pennsylvania earlier this year.

Given all this,we have pretty good reason to think that the polls are underpredicting how well Trump will do in Pennsylvania. The question, then, is by how much?

To answer, we need to decide what we think turnout will look like this year. Once we have a model for this, some estimates of what percent of voters in Pennsylvania will be Republican/Democrat/Independent, in conjunction with data on what percent of Republicans/Democrats/Indepentents are voting for Trump/Clinton, we can use simple arithmetic determine how RPC polls predict the election will go given our preferred turnout model.

Data on how polls are showing people within each party ID group are voting can be easily taken from HuffPollster. The tricky part is estimating what turnout will look like this year.

Here are a few ways it might go:

Pennsylvania will be close. The polls are almost certainly painting a misleading picture. If I had to bet on it, I’d say Trump will win PA, and therefore the election.