The question is asking which entity is not a source of data on unemployment in India. To solve this, we need to evaluate each option and determine its role in unemployment data collection:
- Indian Statistical Institute: Although highly reputable in statistical research, it mainly focuses on training and academic research rather than collecting regular unemployment data.
- Reports of Census of India: The Census collects comprehensive demographic data, including employment statistics, making it a source of unemployment data.
- Annual Reports of PLFS (Periodic Labour Force Survey): Conducted by the National Statistical Office, these surveys are specifically designed to assess labor and unemployment metrics in detail.
- Directorate General of Employment and Training data of Registration with Employment Exchanges: This body deals with employment data, including unemployment through registration records, offering substantial insights into unemployment trends.
Considering the explanations, the Indian Statistical Institute is not directly involved in the collection of unemployment data. Thus, it is the correct answer.