Statistics & Probability : Methods of data collection and organizations 

Methods of data collection we have:- Census survey- Sample Survey

In this section, explain your data collection methods. Describe how you reached the sample/population and how you were able to survey that sample. Point out any limitations in this area of study - 

for example: if you conducted a census, note that (1) everyone in the population did not respond, and (2) thus the results are only for those who responded. Address any biases (e.g., because only the people who responded could be included in the study, this means that the results may not apply to everyone in the population).