recently I tried to prepare a Product List analysis. I was interested in how products on particular possitions are clickable, and then added to the basket and finally purchased.
One of the metrics that affect effectiveness is Product List Views - the number of times a given item on the list was viewed by the user. But when I started to analyze the data, one thing disturbed me. Well, on our website, immediately after entering, 18 products are loaded automaticlly, 3 in each line (and we send to GA ec: impression list for each product). And strangely, according to Product List Views, each item has a different number of views. Strange all the more because all products are loaded immediately. Even more bizarre, even products in one line have different views. And the question - how GA calculates the that metric.
I also checked Google Merchandise Store (to be sure that this is not just our implementation error). And they have similar results. ec: impression list loads when the page is opened for 12 products, 4 per line. in GA the results for each item are different. I checked only for the desktop devices, 1440x900 resolution to minimize the issues of window size and the number of products in the line. Nothing. The results between the products are different
It is also not related with scrolling. in GMS they fire tags on 25, 50 and 75% of page, but events are not related to line with products. On my page there are no scroll events due to infinity scroll we use on product list pages.
So, once again - how GA calculates the metric?