It's calculated for the reporting period that you're looking at (day, month, range of dates, or whatever).

eCPM tells you how much you earn per thousand page views. I don't think it's meaningful on a daily or weekly basis, although I track the monthly figures. eCPM is important because it's a common unit of measurement that allows a way to compare AdSense against other programs. It also lets you know what your page views are worth. For example, if you are making $5 eCPM on a page with AdSense then you have an idea of what to charge for ads on that page... at least $5 and hopefully more.

Are ecpm being dictated by stats or the advertiser itself?

by the stats - its a mathematical function based on the price of the clicks you get compared to the number of page views to get them.

For example if you have 1000 page impressions and
$20.00 earnings
then your ecpm is $20.00, because for every 1000 visitors you are earning $20.00

For example if you have 1000 page impressions and
$20.00 earnings
then your ecpm is $20.00, because for every 1000 visitors you are earning $20.00

Shouldn't that read...

For example if you have 1000 page impressions and
$20.00 earnings
then your ecpm is $20.00, because for every 1000 page impressions you are earning $20.00

?

yeah, yeah, catch me in an error why don't you :-P

Yes, "then your ecpm is $20.00, because for every 1000 page impressions you are earning $20.00" would be correct

:blames the flu:

>> yeah, yeah, catch me in an error why don't you :-P <<

You're welcome! Now get well fast if you have the flu, and pass me some of that $20.00 eCPM please, I could use a large portion of that! :)

"then your ecpm is $20.00, because for every 1000 page impressions you are earning $20.00"

If that is the case how can I make that $20 to $50?

If that is the case how can I make that $20 to $50?

The easiest way would be to increase the page views to 2500

I'm not positive but my gut feeling is that eCPM rates over $10 are uncommon on sites with any sort of volume (say at least 100K page views per month)

I was just pulling numbers to explain the formula, not giving an example of what I get. :)
Man, I wish!

Analytics showed a $9 click on my site last week (if you can believe any of those figures!) I would love to know what niche that ad was in, because it obviously wasn't mine!
And yet, the daily total wasn't up more than a couple of dollars...

Analytics showed a $9 click on my site last week (if you can believe any of those figures!) I would love to know what niche that ad was in...

A couple of years ago I ran an AdWords campaign for a merchant processing firm (sets up credit card processing accounts). They were determined to be in the top position, and the clicks for spot #1 were running between $4 - $5 back then. I suppose they could be double that by now. I'll bet similar industries that involve money (loans for example) get some pretty good clicks.

I think you have to consider a time element when discussing ECPM.

I have some channels that get low traffic but sometimes high value clicks. It's not uncommon for me to check my stats and see an ECPM of $1500.00. But I'm obviously not going to earn on average $1.50 for every impression.

You have to look at it over a period of time for a realistic perspective.

FarmBoy

From the mathematics of statistics (which is what ECPM is - a statistic), its not so much a time element as a 'sufficient size of sample' element.
But, yes, you and I handle that by asking 'has this channel played for long enough for that ECPM number to mean anything?'.
But once you have that sufficient size, time is irrelevant.
A phrase like 'monthly ECPM' would only be useful in informing the listener that you're not talking about some flash in the pan number that resulted from 5 impressions.
I find that much under 1000 impressions can be misleading.

I do have a good giggle immediately after midnight Google to see thousand-dollar ECPMs :)