As per Google there will be two changes in calculating quality score. The first change helps better evaluate the precise quality of your ad - regardless of its position on the page. The second change improves how Google promote ads to positions above the search results.

Let’s look into this in detail

Accurate Quality Score calculation
Till now CTR was the most important factor of QS because it directly shows which ads are more relevant. But as we know ads which are in the top positions have a better CTR (not always).

To calculate the most accurate Quality Scores, it's important that the influence of ad position on CTR be taken into account and removed from the Quality Score.

In the coming days, the portion of the Quality Score algorithm that accounts for ad position will be updated. Google claims that this will result in more accurate Quality Scores, ensure that ads compete fairly for position based on their quality and bid, and show the most relevant ads to searchers by rewarding high-quality advertisers with better ad positions.

Higher quality ads above the search results
Next is about which ads to show in the yellow region above the search results. These positions are particularly valuable to advertisers because they are prominently positioned on the page..

To appear above the search results, in the shaded area, ads must meet a certain quality threshold. In the past, if the ad with the highest Ad Rank did not meet the quality threshold, it was not shown above the search results. But with the latest updates Google will allow an ad that meets the quality threshold to appear above the search results even if it has to jump over other ads to do so. For instance, suppose the ad in position 1 on the right side of the page doesn't have a high enough Quality Score to appear above the search results, but the ad in position 2 does. It's now possible for the number 2 ad to jump over the number 1 ad and appear above the search results. This change ensures that quality plays an even more important role in determining the ads that show in those prominent positions.