A hangman's knot is only appropriate for a long drop hanging. For a suspension hanging (the method usually used in suicides) it serves no purpose. A simple slip knot would have been her best choice.
Killuan said: Late, I know...But while I don't see it as dumb, I have a hard time understanding what makes a image of a little girl who hanged herself...hot?
Let me introduce you to something called necrophilia.
I find this picture dumb in the sense that the artist didn't draw the kicked out chair she would need to use to get up that high.... kidding.
What is supposed to have happened aside, the logical conclusion from this single picture is that she didn't hang herself, but was killed by someone else and placed on the noose to make it look like a suicide.