  Predicting X from Twitter is a popular fad within the Twitter research
subculture. It seems both appealing and relatively easy. Among such kind of
studies, electoral prediction is maybe the most attractive, and at this moment
there is a growing body of literature on such a topic. This is not only an
interesting research problem but, above all, it is extremely difficult.
However, most of the authors seem to be more interested in claiming positive
results than in providing sound and reproducible methods. It is also especially
worrisome that many recent papers seem to only acknowledge those studies
supporting the idea of Twitter predicting elections, instead of conducting a
balanced literature review showing both sides of the matter. After reading many
of such papers I have decided to write such a survey myself. Hence, in this
paper, every study relevant to the matter of electoral prediction using social
media is commented. From this review it can be concluded that the predictive
power of Twitter regarding elections has been greatly exaggerated, and that
hard research problems still lie ahead.
