The quality of the data collection was checked by comparing an individual's average daily dietary intake, calculated from the household survey and individual dietary intake based on 24 h-recall data, respectively.
Discrepancies in data collection were solved checking the regulatory letters against the original source.
All data collection forms were checked for data quality (completeness, consistency, etc) by field supervisors and quality control agents.
Pretested questionnaires were used in data collection and were checked daily for consistency and completeness before the data was entered into the computer.
The quality of the data extracted is high: the medical information is completed by health professionals and data collection is regularly checked.
SES data collection forms were checked for legibility with two rounds of queries regarding missing data (response rate 52%).
All data collection forms were checked by field supervisors for completeness and reliability.
In accordance with the guidelines issued by the Indian Council of Medical Research in 2006 [ 15]e, the overall study and the English versions of all employed data collection tools were checked and approved by the Ethics Committee of the University of Cologne Germanyy).
In accordance with the guidelines issued by the Indian Council of Medical Research [ 41], the overall study and the English versions of all employed data collection tools were checked and approved by the Ethics Committee of the University of Cologne Germanyy).
During the data collection, data are checked on a regular basis to identify out-of-range answers, inconsistent responses, and missing data.
