Kotter's "Career Study" was unique in at least two respects: the duration of the study, and the "n-size" (the number of subjects studied). Traditionally, HBS research has focused on smaller populations, for a variety of reasons.

"You could argue," Kotter told an interviewer midway through the Career Study, "that there are good reasons why we don't generally deal with large n's. If you accept our appreciation of the complexity of reality, you have to grant that it's extremely demanding in terms of time and resources to study even one situation or person. The way much of the academic world gets large n's is by assuming simplistic models about the way the world works, using readily available information to get their n's up in the hundreds or thousands, and then crunching away to produce conclusions of limited value.

"It takes time to develop methods that can be effectively used in large population studies. How long have people been looking systematically at the kinds of questions that we look at here? Fifty years? Seventy years? It was several centuries before medical research became systematized to the point where real research could be conducted on samples of hundreds or thousands. As we learn more, as our knowledge becomes cumulative, our n-size will go up."

John Kotter