Previsões - Eleições presidenciais em Portugal em 2011
Following the seminal work by Choi and Varian (2009) titled "Predicting the Present with Google Trend", I decided to use Google Trends/Insight (GTI) data to forecast the results of the future presidential election in Portugal on the 23/01/2011.
The Portuguese presidential elections may well represent for some aspects a "tough environment" for two reasons:
- There is a high volatility in the opinion polls: for example, the incumbent candidate Cavaco Silvo ranged between 55% and 78%, in the official political polls released in October and November 2010, whereas the main opponent Manuel Alegre ranged between 15% and 35%.
- The internet penetration in Portugal is relatively low, compared to other Western countries (48% of the population as of June/2010 ).
Therefore, I decided to start with Portuguese presidential elections because any eventual problems in my methodology would be much more evident and simple to detect ex-post.
Following the same logic, I considered the following possibilities:
1) Forecasts using GTI data and historical electoral results;
2) Forecasts using GTI data and past political opinion polls;
3) Forecasts using GTI data and historical electoral results with robust regression methods;
4) Forecasts using GTI data and past political opinion polls with robust regression methods;
The first forecasts as of December 2010 are the following ones:
1) Cavaco Silva 51.15 Manuel Alegre 20.90
2) Cavaco Silva 58.43 Manuel Alegre 26.49
3) Cavaco Silva 50.53 Manuel Alegre 20.67
4) Cavaco Silva 57.44 Manuel Alegre 29.38
For sake of simplicity and interest, I considered only the two most important candidates. Finally the latest trends in last 90 days reported by GTI are reported below:
Gigi Bi
