There is not a ‘best’ testing metric for everyone.
There is a best testing metric based upon what you are trying to accomplish.
We’ve put together a quick reference chart to easily let you see what testing metric you should be using:
| What do you want to do? | The metric you should use |
| Increase conversions | Conversion per Impression (CPI) |
| Increase visitors | Click Through Rate (CTR) |
| Increase engaged visitors | Conversion per Impression (CPI) |
| Get the most revenue possible | Revenue per Impression (RPI) |
| Improve quality scores | Click Through Rate (CTR) |
There are two noticeable metrics missing from this list: ROAS and CPA.
Those two metrics should be filtering metrics and not winning metrics.
For instance, if you want the most conversions possible at a $35 target CPA; then you would use CPA as a filter and remove any ad that is above the $35 CPA target and then of the ads left, the highest CPI would be the winner.
These are the cases to use filtering metrics:
| What do you want to do? | Filtering metric | Winning metric |
| Highest revenue above a specific ROAS | ROAS | Revenue per Impression (RPI) |
| Most conversions under a target CPA | CPA | Conversion per Impression (CPI) |
Once you’ve decided what metric you should use as a winner based upon your goals, you can read about that metric in great detail from these pages:
If you’re looking to have these metrics automatically calculated and be informed when your ads hit statistical significance for those metrics, please take a look at what Adalysis has to offer.
