Google announced back in November that it was rolling out changes for AdWords Impression share reporting (the number of impressions received in a campaign or ad group divided by the estimated number of impressions you were eligible to receive).
The company added new columns to separate search and display impression share, and added hour of day segmentation and the ability to apply filters, see charts and apply automated rules using impression share metrics. They also improved the accuracy of how data is calculated.
Today, Google reminds users that it is continuing its plans to phase out the old impression share columns on February 4th, which is coming right up.
"Any saved reports using the old IS columns will need to be updated to use the new columns," says product marketing manager Rob Newton. "If you don’t remove/replace those columns before they’re retired on February 4th, you won’t be able to run those saved reports."
Saved reports will be updated to use the new columns.