In chapter 4, Sachs proposes "a new method for development economics [called] clinical economics..." (82-89). Comparing it to clinical medicine, he saw the need for differential diagnosis--a more flexible way to analyze poverty at the macro level (table 1 on 84).

Sachs discusses differential diagnosis in an online course entitled "Sustainable Development." View the 14 minute lecture (go past any prompt to sign up for the course and complete viewing).

LINK: https://www.coursera.org/lecture/sustainable-development/the-idea-of-clinical-economics-u50le

BOOK LINK: http://www.economia.unam.mx/cedrus/descargas/jeffrey_sachs_the_end_of_poverty_economic_possibilities_for_our_time__2006.pdf