> On-ground reality is completely different from their assumptions. The people designing the survey are very well aware of the reality, imo. The survey is base

> On-ground reality is completely different from their assumptions. The people designing the survey are very well aware of the reality, imo. The survey is based on not just what the answers are, but also what the surveyer sees at the household. They have multiple questions to ascertain the actual number of people living in the household, including questions like "who all slept here last night". Initial samplings of the survey are done with control groups (two separate teams) across different intervals to ensure that the methodology is good enough, and survey results are reflective of the ground-truth. One way to validate the results would be to measure them with another methodology, and it turns out that the relevant result (India's Total Fertility Rate) has a fairly similar value (2.0 v/s 2.1)[1] via the SRS (sample registration system, 2020) which is conducted by another body (census of india) via a somewhat different methodology (tracking life-events by a local body, and using birth/death registrations alongside). It's easy to give up and blame lying survey responders or sampling biases, but there are ways to solve for these, that are being used here. [1]: https://timesofindia.indiatimes.com/india/fertility-rate-declined-by-20-in-india-in-10-years-srs-data/articleshow/94464169.cms https://timesofindia.indiatimes.com/india/fertility-rate-dec...