Please put my mind at ease. I have been running adsense for 5 days now, averaging a fairly low CTR with around 500 impressions per day. Today my CTR how jumped 5x with only 200 impressions. This is probably just a sample size issue since two or three gung ho clickers (without any intent to defraud google) could easily skew the average CTR . Should I be concerned??? Also, is it ok for me to post the actual CTR?
You might also get a good written ad on your site sometimes and get big CTR increase. I have seen a good ad increase my Ctr by 50% in one day.