A person wants to study deafness and mobile phone usage. He collected data on mobile phone usage from government source and deafness from district and private clinics. This type of study is known as:
Ecological study or correlation study is an analytical study. Here the unit of study is population. Results are not applicable on individual person. It is inferior to case control and coho study. Ref: Park's textbook of Preventive and Social Medicine, 21stedition, page-59.
Experimental study
Ecological study
Etiological study
Cross-sectional study