Ada is the Director of the International Statistical Institute since August 2009.

In this capacity she is managing the ISI Permanent Office and implementing the policies as developed by the ISI Executive Committee. Providing support for the organisation of the ISI World Statistics Congress and Regional Statistics Conferences is a key element in her function. She also provides support to the Executives of the ISI Associations and the ISI Committees and Outreach Groups.  Ada is an ISI elected member since 1996 and was Vice President of the IAOS during the years 1997-1999.

Ada organised ISI Workshops for Heads of Statistical Offices in Ethiopia, Senegal, Republic of Korea and Tanzania and contributed as a speaker to the programme of these workshops as well as several conferences.

During the years 1993-2009 Ada was the Head of International Relations in Statistics Netherlands (CBS). In this capacity she co-ordinated the international representation of the CBS in international meetings.  She represented the office in meetings like the EU Statistical Programme Committee, EU Council Working Parties, OECD CSTAT and UN SC.
Before 1993 Ada worked at the Erasmus University Rotterdam, Faculty of Economics, in different functions, the last one policy adviser for the faculty’s research policy and developing international student exchange programs. She combined her full time position with a part time study in Law. In 1993 she graduated Master of Law (Business Law and International Law) from the Faculty of Law.