I have been asked by our marketing department to add Google Analytics custom variable tracking to my company's website. As the website uses server side includes, modifications to the tracking tag roll out globally - maintenance is therefore a headache!

So, if I add the following code (keeping in mind SSI so every page has the same code):

// visitor level tracking, id = 12345
// Record a unique id for each visitor. When they return also track this id
_gaq.push(['_setCustomVar', 1, 'id', '12345', 1]);

// page level tracking
// If the user signs up for our newsletter we set newsletter to true
// Each page they subsequently visit should also mark this as true
_gaq.push(['_setCustomVar', 1, 'newsletter', 'true', 1]);

I don't use GA and the marketing people don't use custom variables, so we don't actually know how or if this will work. Therefore my questions are:-

• Do I want Page, Session or Visitor level tracking?
• What happens when the same code is used on every page?
• Can GA 'overwrite' a setting. For example, if I set newsletter to true on page X and then user navigates to page Y, will the variable also be marked there?