The word "fallacy” refers to something that is false or erroneous. Ecological fallacy is a concept that is related to researchers, the research they carry out, and the erroneous conclusion they deduce from the result of the research. Ecological fallacy is a situation in which a researcher carries out a research on a group and thereafter applies the result from the group to the individual members of the group. In other words, the researcher is erroneously applying the result of the aggregate to the units within the group.
For instance, a researcher carries out some research to discover the educational achievements of the average youth in a certain neighborhood and discovers that the average youth in that neighborhood are high school dropouts. If that researcher sees a youth from that neighborhood and assumes that such a youth is a high school dropout, based on the study of the whole neighborhood, the researcher would be committing an ecological fallacy. The youth, however, could be a genius on the honor roll in high school with offers of scholarships from all of the Ivy League universities.
Another example of ecological fallacy is if a researcher concludes that a man from a certain neighborhood is rich just because a study of the men in that neighborhood revealed that most are lawyers, doctors, rock stars and NBA stars. The truth is that the man could be just an average person who had come to the neighborhood to visit his friend. Ecological fallacy is making sweeping generalizations, which is bound to lead to false conclusions.
The opposite of ecological fallacy is exception fallacy in which someone comes to erroneous conclusions about a group based on the assessment of only a few. For instance, a young boy who is pecked at by a penguin until he starts to bleed concludes that all penguins are crazed, dangerous creatures that must be avoided at all costs. Penguins are not dangerous and will not attack anyone or peck at anyone unless under severe stressors. The young boy has made an exception fallacy, which is his impression of all penguins based on his experience with one penguin. This type of fallacy is at the root of most racism and sexism.
Both ecological fallacy and exception fallacy are the pitfalls that await researchers who base their assessment of individuals based on the result of the general. Researchers must not only carry out general research, but they must also carry out individual-based research to determine if there is a correlation between the outcome of the group research and the individual-based research.