The survey projects NDA winning anywhere between 339 and 365 seats-the highest across all polls.

The India Today - My Axis India post poll study is predicting a landslide victory for the Modi government in the 2019 Lok Sabha election. The survey projects NDA winning anywhere between 339 and 365 seatsthe highest across all polls.

Since the publication of the seat projections, questions have been raised about the survey methodology: How did the pollster arrive at the numbers? Getting the numbers right with a shoddy methodology doesn’t offer deeper insight into the elections. Especially if one wants to answer questions about voter behaviour, which is a key advantage of survey data.

Critics say that media organisations have not been transparent about the polling methodology. How accurate the forecast is will be known in a couple of days. For now, in interest of transparency, India Today is sharing details of the survey methodology of My Axis India, our pollster, and the process behind seat-wise predictions. We are also sharing state-wise vote share for major parties and alliances.

Here are ten key points about India Today - Axis My India election forecast methodology:

1. How was the survey conducted?

Fieldworkers of Axis My India conducted face-to-face interviews in all the 542 Lok Sabha seats that went to polls (election in Vellore, Tamil Nadu, were cancelled). A staff of 500 members were armed with tablets to collect data.

2. Where were respondents interviewed? Was the survey a 'post-poll' or an 'exit poll'?

Even though 'exit poll' is the commonly-used nomenclature, technically speaking, the survey was a 'post-poll' study. The key difference between the two lies in the location and the timing of the interviews.

In exit polls, respondents are interviewed outside the polling booths as people exit after casting their votes. According to guidelines of the Election Commission of India, exit polls are banned.

Post polls are conducted after election day. For the first six phases, Axis My India conducted surveys at respondents' houses.

For the seventh - and the last - phase, the pollster used a different approach. Results of the study are published on the evening of the last day of polling, meaning a post-poll study is not possible.

To account for that, Axis My India conducted a pre-poll survey 4-5 days before the election date. On the day of polling, between 7 am and noon, field investigators interviewed people outside polling booths to validate the findings of the pre-poll survey and check if what people were revealing on polling day matched with the survey data. Note that no data collection was done outside the polling booths as it is not permissible according to ECI guidelines.

3. What was the sample size?

The survey had 7,42,187 respondents across the country and was conducted in every Lok Sabha seat. On an average, there were around 1,400 respondents in every constituency.

4. Why poll on every seat?

Issues vary across constituencies; political and caste equations are different; in alliances, the party that is contesting from the seat may change voters' preference. To capture the local dynamics, Axis My India conducted its survey on every seat.

This methodology, which requires larger resources, bypasses a key issue in election forecasting: converting vote share (which surveys capture) to seat share. Axis My India simply aggregates the seat-by-seat prediction - which is based on the party getting higher vote share on the given seat - to derive the state and national picture.

5. Was the survey sample representative?

A survey sample that doesn't aptly reflect the population is methodologically flawed. Axis My India claims that the survey is representative at the seat level, and by extension, at the national level.

Field investigators are given detailed information about seat-level demographics to ensure a representative sample.

In the survey process, however, some communities might be over-represented, some under-represented. So, after the raw data was collected, Axis My India used statistical methods to weigh the data and factor in the representativeness.

For instance, at the All-India level, 66% men and 34% of women were interviewed, as it was difficult to get female respondents, Axis My India noted. To correct for this, the ratio was extrapolated to 50:50.

6. How does Axis ensure a representative sample at the seat level?

There is no official data for seat-level demographics, especially about the composition of various sub-castes.

For the three broad community groups - SCs, STs, minorities - Census data is available, said Pradeep Gupta, the Chairman and Managing Director of My Axis India. "For further break-up of caste at the seat level, we collated data over a long period of time, based on local inputs, wherever it matters," Gupta added.

Data for each constituency has been weighted by gender, locality, caste group, religion and other demographic factors.

7. How does Axis My India find survey respondents across communities to make the sample representative?

There are two key points: One, based on extensive polling experience, Gupta explained that they have mapped the communities across localities and know where to find them. "This is a big part of our field training. Where to go, how to talk and what to talk about is all part of the training process," Gupta said.

Second, in a given locality, Axis My India interviewed only one or two individuals per community, to ensure that the survey captures the diversity of respondents within the community.

8. How is the interview conducted?

On average, one interview lasts for around 10 minutes, extending to 15 minutes in a few cases, depending on the enthusiasm of the respondent. The interview begins by asking about issues and gradually delves deeper to infer voting preference.

"You first try to understand the issues of the respondent. They believe that someone has come to solve their issues. Then we ask who do you think has the solution to your problems? Has the incumbent government not been able to solve the problem?" Gupta explained. All these questions help the pollster to build confidence among respondents and increase the chance of capturing the true preference of the voter.

9. What other factors are taken into account?

A key metric Axis My India looks at is voter turnout. The pollster estimates an expected turnout figure based on historical data.

If the turnout is lower than the expected figure, Gupta explained, Axis assumes that people from the general and OBC community turned out less. "This is an assumption, and it varies for every pollster. This is our theory," he added.

Accordingly, weights are adjusted.

10. For seat-by-seat prediction, Axis gives a disclaimer

Disclaimer reads: "Seat-by-seat analysis is based on the popularity of the political party, not on that of the candidate contesting on the seat. Hence, the exit poll cannot be held responsible for individual candidates losing in seats where their parties are most popular."

What does this mean?

Gupta clarifies that one shouldn't read too much into this. "It is merely a precautionary measure to ensure individual candidates are not hurt by the prediction," he said.

"We can't write that a given candidate is losing or winning," he added. "This is a prediction, not the verdict. Consider, for instance, if we say candidate X is likely to lose, and she wins, the individual candidate may have an issue."

So, the disclaimer just wants to make it clear that the survey data reflects party popularity on the day of the interview at the time of the interview-not to show a candidate in poor light.

"Ultimately, people vote for the party. When you poll at the seat level, people vote for the party symbol," Gupta said.