. A scholarly article about response rates begins with the following quote:

"Declining contact in national telephone surveys raise serious concerns about the validity of estimates drawn from such research" AND "The percentage of people we interview - out of all we try to interview - has been declining over the past decade or more"

a)What are some reasons for the decline in response rate over the past decade?

b)Explain why researchers are concerned with the impact of the declining response rate on public opinion polls.