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Nonresponse bias and superpopulation models in electoral polls

Publication Type:

Journal Article


Pavia, Jose M


Revista Española de Investigaciones Sociologicas, Volume 134, p.237-264 (2012)



Nonresponse bias (and, to a lesser extent, measurement error) has become the main source of error for electoral forecasts in Spain. Although the post-stratifi cation techniques and ratio estimators currently used in the polling industry reduce deviations, they do not show enough capacity to mend the biases introduced when collecting data. This research reveals how a more effi cient use of the electoral information available outside the sample could help to signifi cantly improve the accuracy of predictions, and uses simulation techniques to show that this may be accompanied by less expensive sampling designs. The analysis, nevertheless, also concludes that the proposed specifi cation is not a panacea and affi rms that there is still scope for reducing nonresponse bias, pointing to several issues for future research.