Bihar Assembly Election Study 2025: Method Note

The Bihar Assembly Election Study 2025 aims to provide data-driven insights into voter behavior, political trends, and constituency-level dynamics. This method note explains the research design, data collection process, and limitations of the study.

PollsMap conducted a post-poll survey for the Bihar Assembly Election 2025 between 7 November 2025 and 13 November 2025. The study interviewed 3,411 respondents across 36 Assembly Constituencies (ACs) and 180 Polling Stations (PSs) in Bihar.

The survey employed a multi-stage stratified random sampling design to ensure representativeness of the state’s voting population. Assembly Constituencies were selected using the Probability Proportional to Size (PPS) method, wherein the probability of selection was adjusted according to constituency electorate size. Within each selected AC, five polling stations were chosen through systematic random sampling. Subsequently, 22 respondents were selected from each polling station using a random walk procedure.

To ensure adequate representation across gender and age, pre-determined quotas were implemented, and field investigators were instructed to strictly adhere to these quotas during data collection.

Data collection was conducted through face-to-face interviews administered by trained field investigators using a pre-designed mobile-based application. The questionnaire was translated into Hindi. The achieved sample closely reflects the social composition of Bihar’s electorate, thereby ensuring representativeness at the state level. A comparison between the achieved sample and Census data is presented in Table 1.

Table 1: Social Profile of Achieved Sample

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