It sure looks like L.A. County, and to a lesser extent Santa Clara County, have experienced an increase in percentage of positive tests. I have no particular clue as to whether it is an increase in illness, or a result of a change in who can get a test. AFAIK, no one has indicated how, say, the tests for patients already sick are handled. (Typically, 2 negative tests are required as part of the decision that you are no longer sick.) One could see this increase as just a return to "normal" after a negative bump when testing was opened, caused by an influx of tests of curious but not sick people.
The one-week average positive percentage for SCC had gotten as low as 1.1% but has bumped up to 1.3% (5 days before current date). L.A. County had gotten down to 4.5% but is now around 6%.
The message quoted is 3 days ago. When I updated my spread sheet with SCC daily testing numbers today, the daily changes prior to 5 days earlier were generally small as expected. L.A. County had a consistent pattern to their changes. When I compare today's testing numbers with those I recorded 3 days ago, L A County testing data had a decrease of 305 positive tests and an increase of 53 negative tests from April 11 to April 28. It appears that LA County generally removed 10-30 positive results daily for two weeks. They did not remove a corresponding number of negative results (if they report 10% positive rate, and remove 10 positive results, a "corresponding number" of negative results would be 90.). Some explanations might be that these were judged to be false positives, or perhaps were for individuals out of the area they are reporting for. The effect of these changes is to lower the % of positive cases in the 3 to 6 week-old data (back to the start of the data that I had recorded, April 11).
LA County shows a 5-day gray window for testing that isn't yet complete. I found that 5-day window to be too narrow. In the last 3 days, the change to number of tests recorded 13 days before the last data shown (3 days ago) increased by at least 10%. The change 7 days before last data shown was an increase of about 100% in cases. The 1-week average in LA County for May 7 - May 13 for data as of May 20 (last datum May 18) was 7.67%; for data as of May 24 (last datum May 21), it is 5.91%.
The one-week average positive percentage for SCC had gotten as low as 1.1% but has bumped up to 1.3% (5 days before current date). L.A. County had gotten down to 4.5% but is now around 6%.
The message quoted is 3 days ago. When I updated my spread sheet with SCC daily testing numbers today, the daily changes prior to 5 days earlier were generally small as expected. L.A. County had a consistent pattern to their changes. When I compare today's testing numbers with those I recorded 3 days ago, L A County testing data had a decrease of 305 positive tests and an increase of 53 negative tests from April 11 to April 28. It appears that LA County generally removed 10-30 positive results daily for two weeks. They did not remove a corresponding number of negative results (if they report 10% positive rate, and remove 10 positive results, a "corresponding number" of negative results would be 90.). Some explanations might be that these were judged to be false positives, or perhaps were for individuals out of the area they are reporting for. The effect of these changes is to lower the % of positive cases in the 3 to 6 week-old data (back to the start of the data that I had recorded, April 11).
LA County shows a 5-day gray window for testing that isn't yet complete. I found that 5-day window to be too narrow. In the last 3 days, the change to number of tests recorded 13 days before the last data shown (3 days ago) increased by at least 10%. The change 7 days before last data shown was an increase of about 100% in cases. The 1-week average in LA County for May 7 - May 13 for data as of May 20 (last datum May 18) was 7.67%; for data as of May 24 (last datum May 21), it is 5.91%.
(05-20-2020, 01:59 PM)M T Wrote: If we make the probably bad assumption that those tested, other than for having symptoms, in Santa Clara County are representative of the population, and we recognized that because this includes those with symptoms, this is an upper bound, then I think a reasonable upper bound estimate of current infections in Santa Clara County is the positive test percentage in the county for a week taken 5 days ago. (5 days ago to allow for all tests to be returned; a week covers the weekend drops).
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By those criteria (average positive % testing, week ending May 13), in Santa Clara County, there are (upper bound) 1.22% that would test positive on any particular day (1.25% if averaged over 2 weeks, so the infection rate is very slowly dropping).
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By comparison, L.A. county (minus Pasadena & Long Beach) numbers for May 13 are 7.67% (1 week) and 5.84% (2 week). L.A. county had two weeks of high testing numbers that drove their average down, but the past week has been about 60% as much testing. (I don't know if it less capacity, less demand, or delayed results.).