Is/are often conducted with large numbers of participants and can even be conducted by phone, email, or mail. surveys case studies university experiments archival research

surveys

Explanation:

Surveys -

It is one of the research method , which require the collection of certain data from a group of people of from different sources for further study , is referred to as surveys.  

Surveys are performed to get information or the viewpoint of of the public , regarding some goods or services , which can further help for the betterment of the product.  

Hence , from the given statement of the question , the correct term for the given statement of the question is surveys.