A 2008 study by Anita Elberse, professor of business administration at Harvard Business School, calls the long tail theory into question, citing sales data which shows that the Web magnifies the importance of blockbuster hits.[37] On his blog, Chris Anderson responded to the study, praising Elberse and the academic rigor with which she explores the issue but drawing a distinction between their respective interpretations of where the "head" and "tail" begin. Elberse defined head and tail using percentages, while Anderson uses absolute numbers.[38] Similar results were published by Serguei Netessine and Tom F. Tan, who suggest that head and tail should be defined by percentages rather than absolute numbers.[39]