CIS poll favors PSOE by over four points and adds 27 seats, analysis shows

The Centre for Sociological Research (CIS) under José Félix Tezanos published its first September barometer of the new political cycle, the first after the Ceuta incident. The poll places PSOE’s Pedro Sánchez at 31% of the vote, keeping him ahead of Alberto Núñez Feijóo’s PP, which registers 25.5%, a gap of five and a half points. Target Point’s re-estimation, which corrects for vote-recall bias, indicates the CIS over-credits the PSOE by more than four points and 27 parliamentary seats, while the PP is under-credited by roughly six and a half points and 30 seats.

Sumar’s share rises only marginally, and Podemos falls by a couple of tenths of a point; other parties such as ERC, Junts, EH Bildu, PNV, BNG and SALF see minimal changes. The bias arises because the CIS does not adjust the sample for respondents’ recollection of their last vote, leading to an eight-point over-weight for PSOE and a four-point under-weight for PP. Similar patterns have been observed in previous months’ barometers.