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

Energy and financial experts say such mistakes are a serious problem and just the latest example of sloppy and incomplete “official” data from the Department of Environmental Protection, which keeps reports on production and waste from the booming, multibillion-dollar resource.