The Business Journal’s daily COVID-19 update story on Tuesday featured data from the county that indicated new cases in Orange County may be declining, based on a seven-day average published in a chart indicating daily cases by testing date.
The county has specified that figures in this chart can fluctuate based on delays in reporting, and thus only provides the seven-day average in the week ending about 10 days prior to the current date.
For example, on Wednesday, the county said there were 592 average daily coronavirus cases reported in the week ending July 6, the most recent available day, which is down from 770 in the week prior.
While the county disclaimed that these figures are still subject to change, the inaccuracies may be greater than initially thought due to even longer testing and reporting delays.
In an email to the journal, Scott Bartell, a public health and statistics professor with the University of California-Irvine, noted that specimen testing, case reporting and data recording by the county health agency can take three weeks or more.
Thus, “the number of new cases shown by specimen date will always appear to be declining in recent weeks in any county, regardless of whether average daily coronavirus cases are actually declining, increasing, or stable over time.”
Each day, the county posts the number of positive cases reported to the agency that day, which is also not an accurate indication of new case trends, as those figures could pertain to dates from more than one month ago.
It’s not fully clear what causes longer-than-typical reporting delays, but it’s likely in part due to the various ways in which the county receives data; sometimes it’s through a straightforward digital communication, other times it’s by phone, physical mail, or even fax machines.
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