Bing announced a brand new change to its Webmaster Tools, concerning the way it calculates Change within the Site Activity widget.

Vincent Wehren explains on Bing’s Webmaster Center blog, “For the metrics Clicks from search, Appeared in search, Pages crawled, and Crawl errors we will be able to now show you the percent change for the chosen date range (as selected within the date selector near the head of the dashboard) in comparison to the prior date range of a similar length. So should you log into your Bing Webmaster Tools account and are taking a look at changes for say a 30-day period to your Dashboard (that is the default setting), the proportion within the Site Activity widget will reflect your relative increase or decrease in comparison with the prior 30-day period.”

Bing Webmaster Tools also will show you absolutely the numbers for the aforementioned metrics for both the present and prior period:

“It’s worth noting that since we store as much as 6 months’ worth of knowledge in Bing Webmaster Tools, we’re — hence — ready to show % change information for periods as much as three months counting back from the last available date,” says Wehren. “For shorter date ranges we will show change information so long as they and their prior period fall within those 6 months of knowledge we store. In other words, you aren’t limited to simply seeing change information for say, just the last 30 days.”

Bing Webmaster Tools will only provide data in your site from the day your site was registered, needless to say.

BIng notes that the changes to the positioning Activity widget also apply to modify info shown at the My Sites page.