Oregon says it will track coronavirus positivity rate consistently across state reports – oregonlive.com:

Calculating the rate should be straightforward: People who test positive divided by total people tested. But the fine print of the calculations is important, and inconsistencies across several different state-issued reports led to varying rates for the same week.

For example, the Oregon Health Authority calculated positivity rates for the week ending Aug. 1 as 5.8% in a schools report, 6.1% in a weekly testing report and 6.2% in an online dashboard.

The reason why? One report used the date someone was tested, another used the date the results were provided to the state or county health department, and the third used a crude calculation tracking changes week to week.

“Data management is complicated,” said Dr. Melissa Sutton, a senior health adviser for the Oregon Health Authority. “We haven’t had the best alignment on methods.”

“We haven’t had the best alignment on methods” is probably the politest, most media-savvy way of saying it. I can think of several other ways.