Red Marble?

You have a bag with 7 marbles, 6 are blue and 1 is red. 7 people will choose, one at a time, trying to avoid the red marble. Is there any advantage to when you choose? (1st , last or other) Some say last since that allows everyone else to take their 1 in 7 chance before you, therefore increasing the chances one of them will get it before you. Others feel it makes no difference, since the odds are 1 in 7 for every one.

Assuming the marbles aren't replaced, then no all spots have equal (1 in 7) chance of losing.  If the marbles ARE replaced and the game ends once someone draws red, then it's better to be last, since the chance of the nth person losing is (6/7)^(n-1)*(1/7)  (this scenario doesn't guarantee that someone loses in the first 7 draws, however)