When Pennsylvania released official data on Marcellus Shale natural gas production last week, there was no mention that numbers from Chesapeake Energy Corp. were missing, meaning the bi-annual totals weren’t close to being accurate. The firm has been a top producer in previous reports.

Energy experts say such mistakes are a serious problem, and just the latest example of sloppy data releases from the Department of Environmental Protection.

Fadel Gheit, a senior oil and gas analyst with New York City based Oppenheimer & Co., called the incident “totally unprofessional.”

But DEP spokesman Kevin Sunday says in a statement issued Monday that it is up to people who use the data to make their own interpretations.

Chesapeake, which is based in Oklahoma City, didn’t immediately respond to a request for comment.