The 20% decline in early-admission applications may be more indicative because an acceptance would be binding on the early-admission applicant. The overall fall in demand for Duke may be masked by the smaller decrease in regular applications, which do not reflect the strength of the applicant's desire to go to Duke (#1 or #7??) or by the overall growth in regular applications nationwide. Also, does anyone know if the quality (e.g. SAT scores) of the Duke applicant pool has changed?
"...does anyone know if the quality (e.g. SAT scores) of the Duke applicant pool has changed?"
We will be able to infer that from the statistics Duke will publish regarding the class it eventually enrolls. I would bet my bottom dollar that it will show a marked decline.