Collection of data is of utmost importance for a research investigation. If the data is not accurate and adequate, the findings of the study are bound to be misleading, however, scientific a research might have been.
The collection of data depends on the field for which the data is to be collected and the methods which are to be used for its collection. The investigator has to decide what methods to use in order to study his problem; whether it is questionnaire, an interview schedule, a case study or observation method or a combination of any of these. The person collecting the data is equally important.