Answer:
a.
Such interest groups at first conducts surveys, seminars, webinars, conferences and in fact all sorts of meetings. Also they send online emails via email marketing using aweber, mailchimp etc. as well as bulk messages via mobile, and also makes the regular phone calls to all whose numbers are available and ask a set of questions from them. The answer that they collect, as well as excel sheets if any give them there data sets. And gone are those days of traditional analysis with knowledge of Statistics and Domain. Now we go for machine learning with knowledge of CS and Stats, and end up with great accurate results.
b.
Advantages:
1)The best machine learning analysis is being used these days. And this is very accurate.
2) We contact public directly.
3) Even public servants are queried before deciding the analysis results.
4) Less money is required for these types of surveys.
Disadvantage:
1. It is limited to only a bunch of people, and nothing more than that.
2. Its a bit inaccurate.
c.
They influence a lot. US election 2016 and 2012 are a perfect example. Public interest in 2012 was with President Obama, and hence he one. His team found out through these interest groups then. And in 2016, it was always looking Hilary Clinton will win, but with good team work, and last moment change in public opinion, and more precisely due to the last moment change in public opinion, President Trump won.
Similarly, in impeachment process as well, public is involved, and their opinion is counted. And they link together all organizations and institutions as the people from same public works at various institutions. And hence, they come together as well.
Explanation:
As explained in the answer section.
