When to track an interaction on a page as a page impression, when as an event, etc.?

The usual track of a page impression is fairly clear and simply: put the code at the end of the page.

But with the growing use of in-page changes to layout and content, when is it OK to log a new page impression and when would it considered to by just an record of an event?

My understanding is that page impression have a strong relationship to ad impressions (at least that's what I understand from my surrounding colleagues).

When I've a page which reveals completely new content to the user without having to reload (everything is already开发者_开发百科 pre-loaded for performance matter), can this be considered a page impression? If so, then it would not relate to the PI/AI math anymore and looks troublesome to me.

Should I rather track that as kind of click event, properly named, but not being calculated to the totals of page impressions?

Some of those user interaction do only simple things like activating a feature for something (e.g. subscribe to a thread, in-application bookmark). I wouldn't call them a new page impression, but an event.

Page impression may be overrated but it's still used as a unit of measure every now and then. Unique users number are as important, too. This question is not about PI vs. Unique user/clients/whatever, but strictly related on how to handle such events.

An interesting problem; the age of ajax makes it hard to draw the line between visits (or impressions). As a simple rule of thumb, your number of counted impressions should = number of ad impressions (a bit circular but true).

In my experience, the method for recording impressions is dependent upon who the data is for:

1. When collecting figures for advertising agencies (such as for the required number of impressions for some CPM ad servers), you must log impressions at once per body onload (per page load or refresh) since that is how often they will refresh your ads - regardless of later dynamic changes on the page.

2. If you are showing ads on your pages and acting as the agency (you have free reign); it is acceptable to count an impression when the content changes significantly as a result of user interaction. I will give an example - the late Multimap by Microsoft would refresh the ads (therefore count an impression) each time the map was dragged (moved) by the user. Facebook updates its ads when you flip between pictures in theater mode (where the images fill most of your screen) despite not actually changing pages - again, only as a result of user interaction.

Method 1 is the industry standard at current, only the most cutting edge ajax sites use 2. Having said that, my website effectively uses 2, although implements 1. I have a lightbox iframe which pops up to display new content (although could just be embedded inline with other content on the web page); meaning the user never leaves the original page whilst generating additional impressions with an implementation of 1 on the page in the iframe - thus I can quote higher impressions that if I were to use straight ajax on the original page with an implementation of 1. Technically, 1 lends itself to recognized tools such as Google Analytics (although in this case 2 can be done just as easily) and will guarentee a refresh of ads inside the iframe (be careful with Ts and Cs of ad servers - many insist on not overlaying/showing more than a certain number per browser view).