The first supervisor of a master thesis has to be from one of the institiutions participating in the program, e.g. the School of Economics FU Berlin. Preferably, the first supervisor gives courses from the Statistics Master program. The second supervisor might be external but needs to be approved by the examination board.
You have to send an email to Mrs. Kaboub (firstname.lastname@example.org) with the following document: http://www2.hu-berlin.de/mscstat/wp-content/uploads/Masterarbeit.pdf
Students must send 3 paper copies (with signed declaration of academic honesty) and 3 USB-Sticks or CDs with a pdf version of the master thesis to the following address:
Humboldt-Universität zu Berlin
Lehrstuhl für Ökonometrie
z.Hd. Frau Kaboub
Spandauer Str. 1