Voter turnout in the first three rounds of India’s general election has shown a distinct increase by historical standards, particularly in some of the more populous states.
This has given rise to speculation that this is bad news for the incumbent United Progressive Alliance (UPA).
The UPA is clearly trailing in opinion polls, but this does not mean that a high turnout is necessarily bad news for the alliance. The chart below shows no obvious relationship between voter turnout and the level of anti-incumbency in Indian elections.
That said, the turnout figures for Bihar and Uttar Pradesh are striking, and it will be worth watching whether they persist in subsequent rounds of voting in those states. This could be good news for the NDA if the increases are being driven by younger voters who — opinion polls show — are leaning towards the Narendra Modi-led alliance.
But if they are being driven by women (as occurred in the 2013 state elections) this could offer some relief to the UPA. Although the UPA performed poorly in those elections, both the CNN IBN-CSDS-Lokniti-The Week (see tables 3a and 3c) and NDTV-Hansa Research Group polls show that the female vote nationwide is divided equally between it and the NDA, while the male vote is decisively tilting in favour of the NDA.
Chunauti 
A recent discussion I attended in Delhi brought up an issue that affects turnout numbers, and (I suspect) their variation from state to state. Namely, many who do not vote are migrants with their registered voting address in their home village or town (rarely city, I would imagine), as certified in their voting card. They cannot afford the time or money to return home to vote, and many of the poor, who are too often resident in places that cannot be proven to be their new domicile, cannot shift their official home address. I would guess that the larger the (out)migrant population of a state (Bihar near the top of the list, probably), the lower the turnout, all other things being equal.
(The remedy for this would be some sort of absentee ballot system, but that would be difficult to mesh with a system using EVMs. Voting by paper absentee ballot is one of the few areas where fraud is likely to occur in the United States, according to one of the other participants in the discussion.)