As well as studying public opinion and political issues, George Gallup conducted extensive research into religious beliefs in the US, having aspired to a career in the church before deciding to join his father’s company.

In an interview conducted for the American Association for Public Opinion Research (AAPOR) earlier this year, Gallup said: “I was thinking about going into the clergy and worked in a black church in Galveston, Texas, for a couple of years, with the idea of going into the ministry. But then I thought of my father’s field and how it could relate to religion and help in finding out how people are responding to God, to the extent that that’s at all possible. So that became kind of a passion with me.”

He ended up working for the Gallup Organisation for half a century, joining in 1954 and becoming co-chairman of the Gallup Poll alongside his brother Alec in 1986 following the death of their father. He stayed on as chairman after selling the company to Nebraska-based Selection Research (SRI) in 1988, and retired in 2004.

Gallup also wrote several books based on surveys looking at religion, and set up a foundation to seek solutions to social problems highlighted by polls.

He died on Monday in Princeton, New Jersey, at the age of 81.

Today the Gallup Organisation, which includes the Gallup Poll as well as Gallup Consulting, Gallup University and Gallup Press, employs 2,000 people in 40 offices around the world.

Frank Newport, editor-in-chief at the Gallup Poll and a former president of AAPOR, said of George Gallup Jr: “He was a great man. He was warm, he was friendly, he was engaging and, as you might expect from someone who was highly religious, cared deeply about the people around him.”

Newport said Gallup’s ability to “marry his personal religiosity with an empirical interest in the data” was particularly unusual.

“Part of his legacy was, he continued and perpetuated the tradition of his father, a strong commitment to integrity and honesty in public opinion research. If you don’t have the public’s opinion, special interests will win out, George always said. The other part is his commitment to religion, but also trying to study religion scientifically. Some religious people scoff at science – he said, let’s embrace it and look at what the data shows. And personally, everyone who met him admired and loved him because he was such a warm, caring human being.”

His daughter Alison Gallup said: “My dad left a legacy with countless people in his kindness, his ethics, his approachability, his humility, his warmth and most of all his faith. He touched a lot of lives. He was my hero.”

George Gallup Jr is survived by his sister Julia, his son George Gallup IV, two daughters, Alison and Kingsley, and two grandchildren.