Santanu Pramanik, Senior Fellow at NCAER and Deputy Director of NDIC, presented on “Statistical validation of a large-scale web survey during the COVID-19 pandemic in India” at the University of Michigan, Survey Research Centre Faculty Seminar. This was a joint work with Abhinav Motheram, Research Analyst, NCAER-NDIC and Soumi Roy Chowdhury, ex colleague at NCAER.
Using data from the COVID-19 Trends and Impact Survey (CTIS) from India, the largest public health web survey, the authors examine the bias in the estimates of vaccine uptake, a population measure which changes rapidly with time. Their findings show that the bias in CTIS estimates of vaccine uptake is not constant over time, rather it increases up to a certain point of time and then decreases. Since the absence of independently verified ‘ground truth’ or ‘gold standard’ for assessing bias in surveys is well acknowledged, they discuss the need for statistical representativeness of web surveys with respect to key demographic characteristics of respondents, which are often correlated with many outcome variables.