But beware: Your estimate may well be based on a lone, repetitive voice that you've mistaken for a chorus, say researchers at the University of Michigan's Ross School of Business.
Professors Stephen Garcia and Norbert Schwarz say that much like the squeaky wheel that gets the grease, a single opinion repeated often enough has nearly as much influence as one expressed by several people.
"What we think others think greatly influences our own personal thoughts, feelings and behavior," said Garcia, adjunct assistant professor of management and organizations at the Ross School. "Quite obviously, an opinion is likely to be more widely shared the more different people express it. But surprisingly, hearing one person express an opinion repeatedly also leads to the conclusion that the opinion is more widespread relative to hearing the same opinion expressed only once."
In fact, one person expressing the same belief three times is, on average, 90 percent as effective as three people each stating the same sentiment once, say Garcia and Schwarz, a professor of marketing and psychology.
In new research published in the Journal of Personality and Social Psychology, the U-M professors, along with colleagues Kimberlee Weaver of Virginia Tech and Dale Miller of Stanford University, conducted six separate studies with more than 1,000 students at six different universities to measure individuals' accuracy in identifying group norms and opinions. The experiments included dividing students into three groups: a three-person control group, a single-opinion group and a repeated-opinions group.
The studies found that an opinion is more likely to be assumed to be the majority opinion when multiple group members express their opinion. However, they also showed that hearing one person express the same opinion multiple times had nearly the same effect on a listener's perception of the opinion being popular as hearing multiple people state the same opinion.
While memory distortion—forgetting who said what and how often—may be one reason why people believe an opinion is more widespread than it actually is, the researchers say that it may not be required to produce the repetitive single-source effect.
"People often rely on social consensus as a cue in assessing truth. If many believe it, then there is probably something to it," said Garcia, who also is an assistant professor of public policy. "Because fluent processing of a statement gives rise to a sense of familiarity, it suggests that one must have heard something similar before, which increases acceptance of the statement.
"Extending this logic, the more familiar the opinion seems, the more perceivers assume that they have heard this opinion many times before."
The researchers found that when people have prior knowledge about where a specific group stands on an issue, they initially are able to discount the effects of repetition. However, after a time delay, an opinion repeated often enough by just one individual may cause others to believe it's true, even when they know the prevailing opinion may be contrary.
In all, since gauging public opinion is an essential component in guiding social interactions, the findings have implications in almost every facet of modern day life, the researchers say.
"On a practical level, our research has important implications for how people may come to estimate collective sentiment in everyday settings," Schwarz said. "To the degree that our impressions of what others think influence our own perceptions of reality, our studies can help inform us about the repetition effect and it consequences."