- Expectancy Bias. If respondents perceive that the questioner has an expectancy of or a desire for, a certain answer, people will more likely give a response that they think will please the pollster.
- Asking respondents to judge the veracity of statements about which they have little knowledge. People often reply to questions about which they know little or nothing because they do not want to appear ignorant or because they wish to please the researcher. In this case, respondents will usually say what they have heard most often to be true — often being strongly influenced by the Acquiescence Response Bias.
So, how does the Yale/George Mason University poll fare when evaluated against these criteria? The two questions most highlighted by survey coordinators in their report, and focused on by media, are as follows:
- “How much do you agree or disagree with the following statements [sic]: ‘Global warming is affecting weather in the United States’?”
- “Some people say that global warming made each of the following events worse. How much do you agree or disagree?”
There are obviously serious problems here. Since they are both agree/disagree questions, they clearly result in Acquiescence Response Bias, boosting the case for U.S. public belief in a global warming/extreme weather connection.
Both of these questions also are poorly formulated because each assumes that the respondent agrees that global warming is actually happening. Few people know that global warming generally stopped in about 2003, and so could not possibly have affected events in at least the last decade. In that sense, they are also leading questions, since they imply that the pollster believes we are still in a warming phase. This then activates the problem of Expectancy Bias.
If survey coordinators had wanted to determine if respondents thought there is a connection between weather and global temperature trends, then they should have asked a neutral, and far more important, question:
Do you think that weather in the United States is being dangerously affected by global temperature trends?
It must be “dangerous” weather change that is being asked about. If it is not dangerous, then while the effect of temperature trends on weather is interesting to scientists, it should not be a public policy issue at all — let alone worth billions of dollars trying to “fix.” Asking whether respondents believed there is or is not global warming should be an independent question.