They shared a common sentiment that economics should be brought closer to mathematics and to statistics (this would later become known as econometrics) and decided to request support from American economist Irving Fisher, at Yale University, to help organize an association to research such topics.

During this period, Roos had also been serving as secretary for the American Association for the Advancement of Science (AAAS) where he oversaw Section K of economics, sociology and statistics.

This position also allowed him to bring together subjects of his interest such as the applications of statistics to the social sciences, and also to invite fellow members of the Econometric Society to lecture and present research on such topics.

In the wake of the Great Depression Roos organized a symposium on unemployment;[8] the papers presented at this meeting were later published by the AAAS in a book entitled Stabilization of Employment.

He quickly declines this fellowship, however, as he was called to be principal economist and director of research of the newly created National Recovery Administration (NRA).

Through a common acquaintance, he met American mathematician Harold T. Davis, a professor at Indiana University who recommended that he look into the Econometric Society.

Besides being the Commission's director he also wrote the first Cowles Monograph entitled Dynamic Economics: Theoretical and Statistical Studies of Demand, Production and Prices[11].

Some examples include Kenneth Arrow (social choice), Gerard Debreu (general equilibrium), Tjalling Koopmans (activity analysis, linear programming), Lawrence Klein (economic fluctuations), and Harry Markowitz (portfolio selection).

While the latter part of Roos' career saw a decline in his academic publications he still found ways to keep himself active and even published in a survey article in Econometrica in 1955.

His main interest was to develop a dynamic theory of economics and he most commonly framed his analysis as a profit maximization problem solved by a firm.

[5] Most of these contributions were summarized in the first Cowles Monograph Dynamic Economics: Theoretical and Statistical Studies of Demand, Production and Prices published in 1934.