Data and source code at https://framagit.org/saji_nh/jp_pcr
The source code, data, and images may be freely used without permission. However, the original data for PCR tests and related statistics were compiled by Tokyo Keizai, and their efforts should be acknowledged by citing their data repository https://github.com/kaz-ogiwara/covid19.
Questions and comments may be addressed to Saji N. Hameed by email (saji'at-mark'u-aizu.ac.jp)

PCR positives without Testing

PCR positives reported without tests

Data source

The data analyzed here is the PCR data reported for each of the 47 Japanese prefecture, and is taken from https://github.com/kaz-ogiwara/covid19/blob/master/README.md

What is reported here?

The data contains some data points where the number of positive PCR counts equal or exceeds the number of PCR tests. Since positive PCR results are always reported along with a test, this disparity needs to be documented and investigated.

  1. In the table below, a summary is provided where the percentage of times this happens is the last column.

  2. The prefectures where this anomaly happens most can be found towards the top of the table.

  3. The total number of positives and tests in such suspicious data points is also provided.

  4. Please click on the prefecture to open a plot which shows the dates at which these suspicious data points are found (top figure).

    • the bottom figure on the plot shows the daily positive PCR counts as the vertical bars. The thick line is the percentage of positive PCR counts relative to the total tests.
    • the background shading on the plots show periods where testing policy has changed. Initially, the PCR tests were carried out on swabs of nasal and throat mucus in symptomatic people (fever above 37.5 C sustained for 3 days or more).
    • The yellow region shows the period when this policy was changed to PCR testing on saliva from symptomatic people.
    • Then on July 17 (grey shade), the PCR tests could be done from saliva swabs on anyone (asymptomatic or symptomatic).
Prefecture No of PCR positives No of PCR tests Percentage of bad points
Kanagawa 1737 0 51.9
Osaka 1007 116 25.1
Nara 215 -209 22.4
Aichi 1018 0 19.7
Ibaraki 139 0 13.1
Chiba 311 90 12.0
Hokkaido 315 33 10.9
Toyama 82 -163 10.4
Okinawa 243 5 9.8
Hiroshima 137 0 9.8
Ishikawa 94 0 9.8
Kyoto 101 2 8.7
Saitama 264 43 8.2
Gunma 73 8 7.1
Fukuoka 258 50 6.6
Shiga 21 2 6.6
Shizuoka 107 0 6.6
Fukushima 31 1 6.6
Kumamoto 79 0 6.0
Nagano 19 1 6.0
Niigata 39 0 6.0
Tokyo 1033 -2959 5.5
Miyagi 41 0 5.5
Hyogo 89 21 4.9
Yamanashi 19 0 4.9
Yamagata 27 0 4.9
Fukui 35 10 4.4
Tochigi 18 2 4.4
Akita 23 5 4.4
Kagoshima 49 0 3.8
Nagasaki 23 1 3.8
Okayama 7 0 3.8
Gifu 30 5 3.8
Saga 11 0 3.3
Wakayama 15 3 3.3
Mie 19 0 3.3
Miyazaki 49 0 2.7
Ehime 8 0 2.7
Oita 12 0 2.2
Kagawa 7 0 2.2
Yamaguchi 9 0 2.2
Kochi 10 0 1.6
Shimane 6 0 1.6
Aomori 10 0 1.1
Tottori 2 0 0.5
Tokushima 0 0 0.0
Iwate 0 0 0.0