If there’s a sudden drop or increase in global pings or tag fires for a conversion action that your campaign is using for Autobidding, this can result in a drop in serving and spending as Google Ads optimizes towards your set conversion action.
If you’re looking at conversion-related metrics like cost/conversion over recent date ranges, be sure to consider conversion lag (also known as "conversion delay").
Example
If you’re comparing performance to a previous period, your most recent performance might not look as strong because some of the people who clicked your ad haven’t converted yet as conversions can be reported up to 90 days after the click. Since you're missing these conversions that may be reported at a later date, but your spend is fully reported, it may appear that you have fewer conversions, a higher cost per conversion.
What you can do
Once you determine how long your conversion delay typically is, be sure to only compare date ranges outside of that period.
Example
If you determine your conversion delay is 10 days, don’t compare last month with this month, as this month will include 10 days without conversions fully reported.
Need something else?
Check other common reasons why your campaign performance is fluctuating.
