A recently released paper found only "only weakly positive and inconsistent gains" in the labor market for stackable credentials, which are defined as certificates and degrees that are awarded in a sequential order, ideally as students progress in their careers.
The study by the Community College Research Center at Columbia University's Teachers College, which was released in November, includes several caveats, such as an acknowledgment that estimated earnings gains from stackable credentials may be imprecise. But, using federal data, the study found no clear labor-market benefits from any of the combination of stacked credentials.
Read more at Inside Higher Ed: https://www.insidehighered.com/quicktakes/2018/01/18/study-questions-value-stackable-credentials