The election turned out to be a close affair between the BJP-led National Democratic Alliance (NDA) and the RJD-led Mahagathbandan (MGB). The MGB fell short due to the poor performance of the Congress in the seats it contested and also because of the AIMIM's spoiler effect. The JD(U) also fared relatively worse than the BJP in the NDA fold, but the latter's significantly better performance than in 2015 helped the coalition sail through, LJP's defection notwithstanding.
How the poll played out
Bihar election data 2020 caricatures
Mapping the seats
The maps show wins in 2020 and 2015 Assembly elections and leads in 2019 Lok Sabha election.
Bihar election data 2020 Map 2020 results
Bihar election data 2020 Map 2015 and 2019
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Strike rate
BJP's strike rate (SR; seats won as a % of those contested) improved to 66.4% from 33.8% in 2015 while that of RJD and Congress fell. Left parties' SR improved significantly to 55.2%. The JD(U)'s fell drastically as well.
Bihar election data 2020 Table 1 Strike rate
Also read: In Bihar, the subdued narrative of the silent voter
Vote share
The BJP had the best contested vote share and only the CPI(ML)(L) came close to matching it. The Congress dragged the MGB down with a low vote share.
Bihar election data 2020 Table 1 Vote share
Head-to-head
The BJP won 78.4% & 60.7% of contests against the Congress & the RJD. The JD(U) won against the Congress handily but fared poorly against the Left & the RJD.
Bihar election data 2020 Table 3 head to head
Also read: Data | How past polls guided the seat sharing strategy between BJP and JD(U) in Bihar elections
Party performances across rural and urban regions
The BJP improved its contested vote shares in 2020 across rural/urban areas from its 2015 numbers, except for a minor drop in urban areas while the JD(U) shed vote share across areas with a major drop in urban areas. The RJD & INC also lost ground.
Bihar election data 2020 Table 4 rural and urban
Party performances across regions in the State
Compared to 2015, the BJP increased its vote share across all regions except Bhojpur. The BJP's strongest show came in Mithila while the RJD's came in Bhojpur.
Bihar election data 2020 Table 5 regions
Also read: Data | Past poll performance across various regions guided NDA seat-sharing deal for Bihar elections
Victory margins
The table shows the number of seats won/led by parties across various margin ranges. Margin is represented as a % of total votes. The number of seats where parties came runner-up across margin-ranges is also noted. 15 seats were won/ led with a <1% margin and another 28 with a margin between 1 and 2.5%.
Bihar election data 2020 Table 6 win margins
Outside factors
The AIMIM and LJP did not win many seats but they secured enough votes to emerge a spoiler for the MGB and NDA respectively.
Bihar election data 2020 Table 7 outside factors
Also read: Employment, finally an election issue
Sources: 2020 Results from the Election Commission of India; maps from Datameet GitHub; past election results from the Trivedi Centre for Political Data; regional classifications from CSDS; rural-urban divisions using night light data from The SHRUG Development Data Lab
