Example 1

In an influential study of progress among primary school children, Bennett (1976), using single-level multiple regression analysis, claimed that children exposed to a ‘formal’ style of teaching exhibited more progress than those who were not. The analysis while recognizing individual children as units of analysis ignored their grouping into teachers/classes. In what was the first important example of multilevel analysis using social science data, Aitkin, Anderson et al., (1981) reanalyzed the data and demonstrated that when the analysis accounted properly for the grouping of children (at lower level) into teachers/classes (at higher levels), the progress of formally taught children could not be shown to significantly differ from the others.

Bennett, N. (1976) Teaching styles and pupil progress. London: Open Books.
Aitkin, M., Anderson, D., et al. (1981) Statistical modelling of data on teaching styles (with discussion). Journal of the Royal Statistical Society A 144: 148-161.