I want to know the rules between the effectiveness of impressions and cost of the clicks. Or revenue depends only on the cost of the clicks? The cost of clicks depends on the CTR? Example:
1 day: 10000 shows, 100 clicks, CTR 1%, revenue = 4$ (0.04$ each click)
2 day: 8000 shows, 100 click, CTR 1.25%, revenue will be more 4$ (because of the high CTR) or will not change (because cost of the clicks not changed)?
That is, revenue is dependent on CTR?
cost of the click depends on the ads itself, it is not a fixed value…let’s say for example thant an amazon ads pay 0.2$ for each click but a mcDonald’s ads would pay 0.4$ (it depends on how much the company wants to invest on the campaign)—> so your eCPM vary not only depending on the CTR, but also on which ads get clicked.
10000 impressions, 100 amazon clicks, 1% CTR, 2$ eCPM
same 10000 impression but 100 mcdonalds clicks, same 1% CTR but 4$ eCPM
I increased refresh time from 30 seconds to 120 seconds, double decreased impressions, CTR and ePCM increased double, but cost of click has not changed, and revenue too, hence has importance only clicks and cost of click? other indicators are derivatives??
no sense to reduce number of useless impressions. they do not affect revenue?
yes, the only thing that really matters is the cost of click, and that is independent on anything you can change sadly…what you can try to change is the number of clicks you get every day 
Changing refresh time and things like that may change your income by increasing/decreasing the chanches that people will click on the ads (maybe too many ads will annoy them and make them less likely to click on them, for example).
eCPM is just an extimate of how much you’ll gain with that particular CTR when you have shown 1k ads…sometimes increasing the refresh rate will increase the likelihood that people will click on the ads, thus giving you a higher CTR…but you’ll show less ads in the same timeframe, so the overall number of clicks will roughly remain the same, hence the income will remain similar too.
Don’t expect anything too great by changing those parameters, but experiment a bit and try to find which settings give you the best income in the end
I received response from development team of AdMob. Increasing update time for banner reduces internet-traffic and reduces energy consumption of battery.
Technical support from Dublin additionally reported - update time needed to adapt to time of average duration of session screen of your program.