LATER NOTE (see comments below): the following advertisement contains a mistake which has now been corrected. Apparently people are to be measured no matter what their nationality, origin or age is. Indeed, more information in Wikipedia on Konfektionsgröße and on the SizeGermany website did not support the wording of the advertisement. In addition, it is absolutely necessary for immigrants etc. to be included: this was done in the Netherlands and France in related projects.
SizeGermany is a project by the Hohensteiner Institut and Human Solutions GmbH to measure thousands of Germans and presumably improve clothes sizes. So I see from an ad by adidas factory outlet in the local rag. Pictures here.
You can apply to join in, but it says in the paper:
Länderspezifische Vermessung durch das Hohensteiner Institut und die Human Solutions GmbH. Teilnahme deshalb leider nur für deutschstämmige Probanden von 6 bis 65 Jahren.
I would have thought they would have taken German passports, but how do they test deutschstämmig?
SECOND LATER NOTE: (Still quoting the (German) comment by a representive of the Hohensteiner Institut) Children must be at least six, but there is no upper age limit – however, you must be able to stand up and sit down during the measuring process.
On top of that, when you are being measured you will be asked what part of Germany your parents come from, because certain assumptions need to be tested: it is believed that people in North Germany are taller than those in the south, and that people in towns are taller than those in the country, which would be important information for clothing retailers.
(Incidentally, the results of the test will only be available to the companies that commissioned it).