President Reagan's primary polling company, Richard Wirthlin's Decision Making Information, has completed a survey for an Arab-American organization that showed Americans more in agreement with Arab positions on Middle East issues than ever.

The Institute for Arab Studies Inc. in Belmont, Mass., which paid an undisclosed amount for the poll, has declared that it shows American views "changing dramatically" toward support for "a much more evenhanded policy" than that of Wirthlin's number one client, Reagan.

But the American Jewish Committee and several independent pollsters have called some of the questions "leading" or "biased," designed to elicit certain answers. An administration poll analyst, who did not want to be identified, agreed there was "some bias" in the questions, but added, "I've seen worse."

He said the findings, allowing for this bias, were "not necessarily a dramatic shift."

Wirthlin, 50, was paid $900,000 by the Republican National Committee for more than a dozen national opinion polls during the 1981-82 election season.

He is now doing a $1 million annual business polling for the White House and the committee.

His office said Wirthlin had no personal involvement in the survey commissioned by the institute. David Leach, project director for the Wirthlin firm, said he was not sufficiently familiar with Reagan's views on the Middle East to know whether the poll results agreed. Reminded that Pat Caddell, President Carter's White House pollster, had been criticized for working for Saudi Arabia at the same time he was polling for the White House, Leach noted that this survey was done for "a group of Americans, some of whom have Arab heritage."

Muhammad Hallaj, former vice president for academic affairs at Birzeit University on the West Bank and now director of the nonprofit Institute for Arab Studies Inc., said it was set up three years ago to provide scholarly research grants and is funded by private endowments, companies and "interested individuals in the Arab world." Its budget this year is $400,000, he said.

An institute board member, Fouad Moughrabi, professor of political science at the University of Tennessee in Chattanooga, said he and a colleague helped write the questions, but denied they were biased. Leach confirmed that some controversial "facts" in the questions were supplied by the Arab-American clients.

"We didn't check them," Leach said. "It was not our role to."

Leach and other polling experts said it is normal procedure for clients to help draw up the questions. "They help us in determining their information needs," Leach said, adding that the final questionnaire was a "fifth draft" resulting from "a back-and-forthing" between his office and the institute.

The poll, a 67-question telephone survey of 1,020 adults nationwide, was done Oct. 6-11 to find out "how would people react if given factual information," said Moughrabi, a Palestinian American born in Jerusalem. "We worked on the assumption that people are not that well-informed."

According to the poll findings, 76 percent of those questioned support the formation of an independent Palestinian state. The question was: "In 1947, the United States supported a United Nations proposal for both a Palestinian and an Israeli state. Do you feel the Palestinians should have the right to establish this state?"

The 24 percent who answered "no" or had no opinion were then told that "half of the 4.5 million Palestinians in the world are stateless refugees and the majority of the remaining half live under Israeli occupation in the West Bank and Gaza." When the question was repeated, 69 percent of those who had said no the first time decided to agree.

Milton Himmelfarb, director of research and information services for the American Jewish Committee, said the issue "was presented in such a way as to elicit a response desired by the sponsors." He added that he could easily devise a question that would get a different answer.

To another question, half the respondents said the Israelis were not justified in invading Lebanon. The 42 percent who thought they were justified were asked: "If you knew that during the cease-fire between Israel and the Palestine Liberation Organization from July, 1981, to June, 1982, the PLO observed the cease-fire and launched no rocket attacks while Israeli bombing caused the deaths of almost 100 people, would you still feel that Israel was justified in invading Lebanon?"

To that, 47 percent of those who had approved the invasion before now answered no.

"That's pretty close to a loaded question," said Paul Sheatsley, senior survey director of the National Opinion Research Center at the University of Chicago.

A polling company, he said, "should know more than the client about how to write the questions and should assume the responsibility for making sure the survey is technically valid."

Albert Cantril, director of the Bureau of Social Science Research, agreed. "There is a pro-Palestinian tilt . . . . They provide information on the pro-Palestinian side for all the issues."