This happens due to a stacking of the bids for the already existing bid adjustment in the campaign. When we show a suggestion for a bid change, we take into consideration the current performance which is based on your currently existing bid adjustment. Here's an explanation on how it works:
If there is an existing bid adjustment of, for example, 35% and you've set the range as -50% to 50 in "Set bids", your new bid can vary from (-50%+35%) to (+50%+35%), creating a range of -15% to +85%.
The "Set Bids" option can suggest the same bid adjustment for all campaigns if the calculated bid adjustments for all your campaigns is greater than the allowed range for min-max adjustment.
For example, if the range defined is -50% to 50%, and the bid adjustment calculated by the tool for all the campaigns is greater than 50%, then a bid adjustment of 50% will be suggested for all the campaigns.
To fix this, you can either increase the "allowed change%" or alter your goal value.
If you choose a Conversion based metric (like Cost/Conv or Conv. Value/Cost), the system will only recommend bid adjustments for locations with conversions.
You may not see all the campaigns in the Geo Bid Adjustment optimization if you have campaigns which have had less than or equal to 5 clicks in a selected location for a selected date range. This has been incorporated in the tool to reduce noise and make sure you're viewing data that has some significance. If you increase the date range, you'll notice that the number of campaigns shown increases as they have more data for a longer date range.
The Geo and Device Bid Adjustment tool only looks at data for ad groups that are currently active. This is because you don't want to set bid adjustments for entities that are active based on data from paused entities. In AdWords, the data for ad groups that are paused is also included, therefore, you might see a difference in the data for both tools.
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