In the 1930s, william f. whyte moved into a low-income italian neighborhood in boston. for nearly four years, he was a member of the social circle of "corner boys," which he described in street corner society. his goal was to gain greater insight into the community that these men had established. the type of research technique that whyte used is called

I believe the answer is: participant observation

In participant observation  technique, The data collecting process is being done by either observing the event from a close distance or by directly involved within the event. This research technique tend to be favoured if the researchers want to include qualitative data as a factor to create a conclusion.

sounds good to me mate!

answer; pentagon papers, vietnam draft-resistor, james dean, american revolution;