How Often Does Adwords Re-Evaluate (Change) Min Bid?

[bigdealioo]

Is it based on a time period, such as every 24 hours or on every X clicks or every Y impressions? It's obvious that Adwords is looking at CTR every so often and adjusts the Min Bid to "optimize for CPM" (translation: squeeze as much $ as possible out of every advertiser).

My questions is.. exactly .. how often?

[Pengi]

It's obvious that Adwords is looking at CTR every so often and adjusts the Min Bid to "optimize for CPM" (translation: squeeze as much $ as possible out of every advertiser).

Not sure I'd agree with you there.

I find the most (but not all) of my minimum bids have not been changing. 1 exception was a few weeks back when G changes the algorithm and introduced a new set of minimim bid values.

Where I do see some changes I believe is is after a number of impressions or clicks rather than a period of time.

I have hear about a 3 monthly purge on the Quality Score, but I've not experienced this myself - yet!

[trannack]

I notice a whopping change every three months. Inbeween I can see no particular pattern. I would guess there is some logic in it - but am not sure - perhaps its by domain name, number of impressions, CTR.......and so on. Who knows, but I'm sure Google will not divulge their parameters. Maybe the AWA would like to comment?

[QualityNonsense]

I've never had problems with minimum bids until the last couple of weeks. Keywords which have been slow but steady performers suddenly have slightly higher minimum bids. One of my new campaigns (promoting a reasonably well-known UK mobile phone site) has been hammered by $10 minimum bids (despite little competition) over the same period.