Survey research professionals are well aware that the way respondents answer a question can be influenced by the questions that precede it. “Context effects” can occur when results to a specific question vary when it is asked in different surveys, especially when those surveys cover different topics.
Some context effects are easy to anticipate and avoid. … But context effects can be unexpected and may not be discovered until a question has been repeated many times and it becomes apparent that the same question in different contexts yields different results. This is what occurred for Gallup’s long-standing trend question on sympathies toward the Israelis and Palestinians in the Middle East conflict. CONT.
Jeffrey M. Jones, Gallup