Impressions going up, but eCPM drops accordingly?

[kineda]

I've been following my adsense earnings today. The readership of my site is growing pretty rapidly at over 2000+ impressions a day. However, something quite strange is happening that didn't happen before(and maybe this is what Smart Pricing is all about).

The CTR of the site hasn't changed much. However, in the morning the eCPM is high even when the page impressions are low. I'm assuming when you reach 1000 impressions, your earnings equal the amount that was listed in the eCPM column correct? And when you double the page impressions, you should be earning twice the eCPM?

However, my eCPM keeps dropping throughout the day. So even though the page impressions are increasing, the earnings aren't.

Any insight?

[woodrow222]

Saturation. Advertisers have a set budget. If your site is at saturation point (high ranking, taking the lions share of ads) no matter how much you improve or how many clicks you generate, you will exaust the advertisers budget.

This is one reason multiple ad units do so poorly on some sites.

[kineda]

Just so I understsand this, here's an example I made up:

Let's say at 10:00am you see this:
Page Impression: 100
Page eCPM: $1.00
Your earning's: $0.10

At 2:00pm you check again:
Page Impression: 500
Page eCPM: $0.50
Your earning's: $0.25

And again at 5:00pm:
Page Impression: 1000
Page eCPM: $0.25
Your earning's: $0.25

Can you expand on this a bit more? Are you saying the advertiser had a set budget of 25 cents?

[elsewhen]

kineda... i wouldn't focus too much on stats that you get DURING a day. i suspect that some of the numbers aren't posted in unison...

looking at yesterday's data, or any data from the past is the most reliable way to make any analyses.

[kineda]

Understood, but what if this is an ongoing trend? ie. it happened yesterday and the week before.

[moneyraker]

Kineda, have you checked if the drop in CPM is due to a drop in CTR or a drop in EPC? If it's a drop in CTR, then your readers at night click less than your readers in the morning. In my website, I noticed that the Europe-US zones post higher clicks than the rest.

[elsewhen]

moneyraker... that could be it... but i also think that google may hold back on some clicks until they have had a chance to verify them. my eCPM tends to increase before the end of the day. other types of reporting phenomena, entirely on google's end, could also help explain intraday fluctuations.

i'm not saying that something else isn't going on, just saying that it COULD be attributable to reporting phenomena.