Much Higher CTR ad is showing lesser than lower performing ad

Yeah, that happens sometimes. I can't explain it other than some sort of glitch in the system. I create a new ad to replace another and for some reason, the control ad gets more impressions instead of the usual 50/50 as I ask in settings.

Doesn't matter if the new ad/lower volume has a higher CTR. That's taking it out of context anyway because you don't really provide enough information. For one thing, it gets less impressions so it's statistically insignificant.

There are some other campaign-level settings that may affect what you are seeing. Basically, any setting that gives control to the system instead of you could lead the system to trip over itself, manual bidding over anything else for instance.

I don't really have a solution for you other than check those settings. Only recommendation is to pause the ads or group and restart later (say an hour or two) and see if that "resets" the system. Or pause the ad you believe is the lesser performer, maybe replace it with another.

That may not give the results you expect however. You are looking at just CTR and basing your assumption on that. There's more to it than that and the system takes that into account to deliver what it believes is the best for all (the searchers, you and Google). It could be that your 4% ad is really better; you don't mention the ads' positions and that is a factor. The 10% ad may have only a couple of clicks and that goes back to statistically significant data: it's not.

Thanks for reply

ill try to stop the low CTR ad and see what happens

It's because the ad with a CTR of 10% likely has a common headline that other advertisers use so I think what Google does is limit the amount of the similar headlines once again using algorithms. I think Google doesn't want 4 ads on top with the same exact headline. So yes it may make sense to pick an ad with a ctr of 3% over an ad with a ctr of 4% just because of this.

What Google recommends is to have multiple ads instead of one ad and under campaign settings you set ad rotation to optimize for clicks instead of doing the do not optimize ad rotation.

https://support.google.com/adwords/answer/112876?hl=en

Keep in mind: The ad with the highest CTR may not always be the one expected to get the most clicks. That’s because the number of clicks an ad is expected to get is also affected by how often an ad is eligible to enter an auction. Expected CTR is only one factor of Ad Rank, which also considers landing page experience and ad relevance (among other factors) when determining your ad’s position and whether it will show at all. So a more relevant ad with a better landing page experience but a lower expected CTR could be eligible to show on search results more often. That can, in turn, lead to a higher overall number of expected clicks.