What counts as a viewable impression?
An impression is viewable when at least 50 percent of the ad is on screen for 1 continuous second. Only viewable impressions of paid campaigns earn.
An ad is counted as viewable when at least 50 percent of it is on the visitor’s screen for 1 continuous second. An ad that is loaded but never scrolled into view, or that passes by faster than that, is an impression but not a viewable one.
Housing Market Publisher pays for viewable impressions of paid campaigns only. Your dashboard shows impressions and viewable impressions side by side, for each website and each slot, so you can see how many of the ads on your pages were really seen.