On Sunday morning (or Saturday late night in US), we received an email from Google AdWords, about an error in reported conversion values. The AdWords users who use AdWords Scripts, automated reports or the AdWords APIs, are affected by this error.
Between Thursday, 21 May 2015 12:52 PM and Saturday, 23 May 2015 12:22 AM Pacific Daylight Time ie. for about 36 hours, the data in reports was incorrect. As per the email, it seems, only the values of Clicks, Impressions and Cost (and their derivates like CTR, CPC,..) were correct. Rest of the columns returned incorrect values. Of which, the conversion-related columns are most crucial. If you have an AdWords script that makes changes (such as modifying the bid, pausing the keywords/ad groups/campaigns,..) to the account based on the conversion data, it probably made incorrect decisions during this window. Obviously, accounts that use a third-party bid management software, would also be affected.
AdWords API developers reported this problem on AdWords API forum. An user reported that this problem existed even for the reports downloaded from the AdWords web interface. The AdWords API Team member confirmed on Sunday that the problem has been resolved.
The email says, “at least one of your reports may be affected,” which leaves two question unanswered. One, did this problem affect only some or all of the AdWords accounts that use AdWords Scripts, automated reports and APIs? Second, did the web interface showed incorrect values as well during this window?
I would guess, the large accounts that make frequent bid changes are probably among the worst affected. If the number of conversions were reported higher than the actual, the bidding software probably increased the bids, causing you to spend more than you intended. On the other hand, if the conversion data underestimated the real numbers, the bids may have gone down to take into account the fall in conversion. In which case, the account probably saw lower average position, resulting in lower click volume.
To be safe, if you have made changes to your account during this window based on conversion metrics, you should review your changes. Please note that the aforementioned time is Pacific Timezone. You should convert that to your respective timezone (local or of the account) to find out the window in which your accounts were affected.
The full text of the email.
Dear AdWords Advertiser,
Due to a temporary issue, automated reports downloaded in AdWords incorrectly reported certain stats between Thursday, 21 May 2015 12:52 PM and Saturday, 23 May 2015 12:22 AM Pacific Daylight Time. The issue has been fixed and you will see correct stats if you download those reports now.
If you downloaded a report during the times stated above, or used automated scripts that rely on these columns, you may have received incorrect stats from reports for all stat columns other than Clicks, Cost and Impressions (and their ratios). The most commonly affected stats were Conversions columns (ConversionRate, ConversionValue, EstimatedTotalConversions, etc.), Impression Share columns (SearchImpressionShare, SearchRankLostImpressionShare, etc.) and Invalid Click columns (InvalidClicks, InvalidClickRate).
During the time of the issue, you may have seen the following for the affected stats columns:
If the column was a regular stats column (e.g., Conversions), the reported value may have been greater than the actual value.
An incorrect value (either greater than or less than the actual value) may have been reported for columns derived from one or more regular stats column (e.g., ConversionRate, since it is calculated as Conversions / ConversionTrackedClicks).
Our logs show that at least one of your reports may be affected by this issue. While we’ve fixed the issue, we recommend that you re-run these reports and use the corrected data. If you downloaded and stored this data in your local database or used the data to make bidding changes, these will need to be updated. AdWords automated bid strategies were not impacted by this issue.
We apologize for any inconvenience this issue may have caused you. Please contact us or your Google representative if you have additional questions.
The AdWords Team