Change bids and targets after switching from last-click attribution to data-driven attribution

Changing your attribution model from last-click to data-driven attribution (DDA) helps determine which of your clicks or keywords are most impactful. DDA assigns a value to each click and keyword that has contributed to the conversion process and helps drive additional conversions at the same cost-per-action (CPA).

This article explains the process of changing your bids and targets after switching from last-click to data-driven attribution. Learn more about attribution models for conversions and bidding

Update your bids and targets after changing attribution models

After you change your Google Ads attribution model, you’ll want to update your bids and targets to keep your performance stable.

If you're bidding manually, there will be no performance impact (positive or negative) until you update your bids and targets based on the new data. However, changing targets is especially important if you're using Target CPA or Target ROAS bid strategies.

Example

Imagine you're using a Target CPA bid strategy, and you update your attribution model in Google Ads to data-driven attribution. Let’s say you have two campaigns with the following last-click performance in the “Conversions” column over the last two weeks:

  • Brand (lower-funnel) campaign: $5 CPA, 200 conversions
  • Generic (upper-funnel) campaign: $20 CPA, 50 conversions


Since you're using Target CPA bid strategy, the targets above are also the targets used in bidding. 

Now say you look at the “Conversions (current model)” column, which reflects data-driven attribution performance, and see the following:

 

  • Brand (lower-funnel) campaign: $6.67 CPA, 150 conversions
  • Generic (upper-funnel) campaign: $10 CPA, 100 conversions

If you’ve left the CPA targets at the original $5 and $20 while switching from “Last-click” to “Data-driven” attribution, Smart Bidding would adjust the bids, as follows:

  • Reduce bids on your “Brand” campaign (since the CPA target of $5 is lower than the data-driven model CPA of $6.67) 
  • Increase bids on your “Generic” campaign (since the CPA target of $20 is higher than the data-driven model CPA of $10)

Adjust your bids and targets for Target CPA

  1. In the “Campaigns” tab, look at the performance for conversion actions according to your newly selected attribution model by adding the “Conversions (current model)” and “Cost / conv. (current model)” columns to your reports. Learn how to add and remove columns in your statistics table.
  2. Compare these columns to the “Conversions” and “Cost / conv.” columns to see the change from the previous model to the current model. 
  3. Calculate the percentage change in “Cost / conv.” column. 
  4. Set your new CPA targets by adjusting your previous CPA targets by the same percentage change, at the campaign level, as illustrated in the example below.

Note: When selecting the date range for your analysis, exclude the most recent 14 days to avoid the effect of time lag between click and conversion.

Example

Say you updated your attribution model for a specific conversion action on September 1. Because you should exclude data from the last 14 days (August 18-31) from your analysis, you could calculate your Target CPA (tCPA) adjustments by using the data from August 4-17.

Campaign Cost Conversions Cost/conv Conversions (current model) Cost/conv (current model) tCPA adjustment
Generic 1 $250 200 $1.25 280 $0.89 -29%
Generic 2 $500 600 $0.83 520 $0.96 +16%

As you can see in the table, for the “Generic 1” campaign, there is a $0.36 decrease in cost per conversion using the current model (from Google Ads attribution). To adjust this, decrease your tCPA down 29% (0.36/1.25=0.29).  

For the “Generic 2” campaign, there is a $0.13 increase in cost per conversion using the current model (from Google Ads attribution). To adjust this, increase your tCPA up 16% (0.13/0.83=0.16). 

Adjust your bids and targets for Target ROAS

  1. In the “Campaigns” tab, look at the performance for conversion actions in your newly selected attribution model by adding the “Conversion value (current model)” and “Conv. value / cost (current model)” columns to your reports. Learn how to add and remove columns in your statistics table.
  2. Compare these columns to the “Conversion value” and “Conv. value / cost” columns to see the change from the previous model to the current model. 
  3. Calculate the percentage change in “Conv. value / cost” column. 
  4. Set your new ROAS targets by adjusting your previous ROAS targets by the same percentage change, at the campaign level.

Note: When selecting the date range for your analysis, exclude the most recent 14 days to avoid the effect of time lag between the click and conversion.

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