The instructions for the extra snippet of code to track Adsense says to add the snippet to "a" page. What exactly does that mean? Can I add it to my header thus having it show up on "all" pages without causing trouble or am I limited to adding it to one page. It is for a wordpress site.
the analytics code must be on each page you want tracked. otherwise there is no signal to tell GA what has been served. i would also suggest putting any tracking codes in your footer to improve page load and rendering times.