Sources of data

Data come from two kinds of source:

• Primary data are collected first-hand by the researcher.
• Secondary data come from published or unpublished sources collected by someone else.

Primary methods:

• personal observation in the field;
• interviews;
• a questionnaire (filled in by the respondent himself) or a schedule (filled in by a trained enumerator who asks the questions, so even people who cannot read can take part);
• field kits and transducers (instruments that measure things like soil, water or air quality).

Secondary sources:

• Published: government publications (the Census of India, the National Sample Survey), quasi-government bodies, international organisations (the United Nations), private publications, newspapers and the internet.
• Unpublished: patwari (village land) records, municipal plans, and the records of companies and associations.