I guess this is a reference to the joke, "no, what we know is that there is at least one sheep, at least one side of which is black."
Unless we disbelieve what the guy said: we do know that they have at least the concept of a tank. He didn't actually say that they had any. That would have been a conversation-ending question for me to ask him.
I don't know what those sheep statisticians would say if they hadn't seen the "black sheep" themselves and had to rely on the testimony of other people. You can't only believe what you've seen for yourself.
As for all the people downvoting that: lighten up. It's a joke. Welcome to NATO.
> and had to rely on the testimony of other people
The sheep joke is not about believing people's reports or not, but about what may or may not be deduced from a report, given that it is accurate and true.
