Pew is a family name, not an acronym. The four children of Joseph Newton Pew, who founded the Sun Oil company, created and funded The Pew Charitable Trusts in the late 1940s. Full name is The Pew Research Center for the People & the Press. The Pew Research Center for the People & the Press is an independent, non-partisan public opinion research organization that studies attitudes toward politics, the press and public policy issues. In this role it serves as a valuable information resource for political leaders, journalists, scholars and citizens.
No, it is not reliable to a large extent. "For most of our national surveys of the general public, we conduct telephone surveys using a random digit sample of landline and cell phone numbers in the continental United States"(Pew research center). Even though this may seem like a random sampling method, but it is to a large extent still a bias sampling method. The only thing random here is the phone numbers they call. Those who will take their time and answer the questions are only those who are interested in it. This is a kind of voluntary response, where the people who care enough to answer are not necessarily a statistically representative sample of the actual population. Moreover, some members of the intended population are less likely to be included than others. As it said in this method which they use most of the time, it is restricted to not only those who are in the continental United States, but also they must process a hand phone or home line. In conclusion, a biased sample causes problems because any statistic computed from that sample has the potential to be consistently erroneous. The bias can lead to an over- or underrepresentation of the corresponding parameter in the population. Thus Pew is not reliable to a large extent. However there are also part that can be trusted with is statistical data collected from authorizations or government with statistics of the entire related populations such as GDP, average income etc, can be trusted.