The term used when the aggregated data (for instance, aggregated over different areas) are analysed and the results supposed to apply to the relationships at the individual level. In most of the cases analyses based on aggregated level means give conclusions very different
from those which would be obtained from the analysis of unit level data. An instance from the literature is the correlation coefficient of 0.11 between illiteracy and being born in foreign calculated from person level data, compared by the value of -0.53 between percentage illiterate and percentage foreign born at the State level.