Is Early Voting Related to General Election Margins?

The first week of early voting has Democrats abuzz and Republicans sounding the alarm bell.  But does the enthusiasm in early voting translate to greater support for candidates in November?  After all, November is a long way off and the campaign has just begun.  The state’s early primary date also gives even more time for the Republicans’ twin advantages of incumbency and funds raised to expand their margin of victory. 
 
Democrats will be happy to learn that there is a relatively high correlation between cumulative three day early voting and vote share of the top of the ticket candidate in the subsequent November election – a .660 correlation overall.*  The effect is strongest for senate elections (correlation is .712) and presidential elections (correlation is .624) but relatively strong for gubernatorial elections (.595).

he effect for Republican 3 day early voting turnout is mixed but clearly not as strong as for Democrats.  Overall, the correlation for top of the ticket vote share is -0.348, posting a negative linear relationship.  The strongest results are for presidential elections (correlation is .920) but the weakest are for senate elections (correlation is -0.436.).  Gubernatorial elections fall in the middle – early voting in these cycles isn’t as good a harbinger of more Republican votes in November.  

Democrats have reason to be enthusiastic but not celebratory about the massive jump in early vote turnout.  If past trends predict current ones, Democrats can count on an larger vote yields in November.  With no presidential race to excite the faithful, Republicans may be looking at smaller margins in November.  But, with 10 months to go until Election Day, a lot can happen. 
 
 
* Correlation coefficient estimates a number from -1 (negative relationship) to +1 (positive relationship) to represent a linear dependence between two numbers.  Elections data from Texas Secretary of State, 2002 to 2016.  “Top of the ticket” candidate is the race that appears first on the ballot, unless otherwise noted.