The Election Commission of India (ECI) has attracted criticism for reducing the Voter Verified Paper Audit Trail (VVPAT) based audit of Electronic Voting Machines (EVMs).
VVPAT audit
The VVPAT-based audit of EVMs is a simple problem of statistical quality control.
It is very similar to the “lot acceptance sampling technique” that is widely used in industry and trade.
If the number of defectives found in a randomly drawn statistical sample is less than or equal to a specified acceptance number, the lot (or ‘population’) is accepted; otherwise, the lot is rejected.
‘Defective EVM’ is defined as one with a mismatch between the EVM count and the VVPAT’s manual count of voter slips due to EVM malfunction or EVM manipulation.
Unlike industry and trade where a few defectives in the sample may be tolerated, in the context of elections, the acceptance number will have to be ‘zero defective EVM’.
In other words, even if there is a single instance of mismatch between the EVM count and VVPAT manual count in the randomly drawn sample of EVMs, the ‘population’ of EVMs from which the sample was drawn should be ‘rejected’.
In this case, ‘rejection’ means non-acceptance of the EVM counts for that ‘population’ and doing manual counting of VVPAT slips for all the remaining EVMs of that ‘population’.
In such a scenario, the election result should be declared only on the basis of the VVPAT count.
VVPAT-based audit of EVMs involves three essential elements
A clear definition of the ‘population’ of EVMs from which the statistical sample would be drawn.
It could be all the EVMs deployed in an Assembly constituency, a Parliamentary constituency, a State as a whole, India as a whole, a region (or group of districts) within a State, or any other.
The population size (N) could vary widely depending on how we define the ‘population’;
determination of a statistically correct and administratively viable sample size (n) of EVMs whose VVPAT slips will be hand counted;
application of the ‘decision rule’, viz., in the event of a mismatch between the EVM count and the VVPAT count in the chosen sample of ‘n’ EVMs, the hand counting of VVPAT slips will have to be done for all the remaining (N-n) EVMs forming part of that ‘population’.
The ECI has not specified the ‘population’ to which its sample size relates. It has not explained how it arrived at its sample size.
It has maintained silence about the ‘next steps’ in the event of a mismatch between the EVM count and the VVPAT count in the chosen sample, and it has glossed over reported cases of mismatch.
A system of VVPAT-based audit of EVMs in which these three vital issues have been left vague or unaddressed is categorically unacceptable.
Way forward
The Supreme Court has been indulgent towards the ECI due to its plenipotentiary role in the conduct of elections under Article 324 of the Constitution of India.
But the Supreme Court cannot continue to turn a blind eye to the ECI making a mockery of the VVPAT-based audit of EVMs thereby defeating the very purpose of introducing the VVPAT.
It must compel the ECI to make public how it has defined the population, how it has arrived at its sample size, and most importantly, its decision rule in the event of a mismatch.
Only then, the Supreme Court’s order of 2013 on VVPAT would be implemented faithfully in letter and spirit.
