My site used to have $10+ eCPM but these two days the eCPM has dropped significantly to $3-4. The CTR is about the same but lower earnings. that is lower pay per click. The contents of the site has not been changed since the beginning. Even i can see similar ads (same company) when served from the beginnning. Anyone notice this or it;s only me? Summer blues (so that advertiser lower their bid?) ?
Finally, I found the reason for the low payout these few days! possible that someone advertise on my site with low bid. After filter those ads out, the pay rate is higher now. So i turned off the on-site advertisement.