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. 2022 May 24;15(7):726–733. doi: 10.1016/j.jiph.2022.05.011

Table 3.

Partition models parameter using decision tree method on the daily cases and daily deaths data segregated on the Beta, Delta and Omicron outbreak periods in South Africa a.

N Death/dayb LogWorthc R2b AICsd
Beta Outbreak Periode
Recovery rate ≥ 89.11 % 103 126.6 ± 90.4 5.924 0.533 1907.7
Recovery rate < 89.11 % 48 427.6 ± 194.1 2.128
Case/day < 5297 100 124.7 ± 90.0 3.531 0.507 1915.9
Case/day ≥ 5297 51 413.7 ± 197.3 1.765
Percent positivityf < 17.23 % 119 162.6 ± 138.5 2.868 0.359 1955.3
Percent positivityf ≥ 17.23 % 32 444.3 ± 205.1 0.919
Delta Outbreak Periodg
Recovery rate ≥ 91.92 % 133 83.1 ± 63.9 10.126 0.565 2573.5
Recovery rate < 91.92 % 81 312.1 ± 136.6 0.211
Case/day < 5574 120 75.3 ± 57.4 10.189 0.521 2594.1
Case/day ≥ 5574 94 290.3 ± 140.9 2.185
Percent positivityf < 16.20 % 133 118.2 ± 122.9 0.899 0.200 2703.8
Percent positivityf ≥ 16.20 % 81 254.5 ± 147.6 0.919
Omicron Outbreak Periodh
Recovery rate ≥ 96.31 % 59 31.4 ± 38.9 0.903 0.152 1744.9
Recovery rate < 96.31 % 92 97.8 ± 93.7 1.913
Case/day < 2111 66 38.2 ± 55.3 0.651 0.127 1749.2
Case/day ≥ 2111 85 98.1 ± 92.1 3.012
Percent positivityf < 15.94 % 63 26.9 ± 27.2 0.411 0.209 1734.4
Percent positivityf ≥ 15.94 % 88 104.0 ± 94.7 5.304
Backlog counti = No 131 56.5 ± 67.5 ----j 0.223 1731.7
Backlog counti = Yes 20 172.4 ± 107.6 ----j
a

Using the analysis platform, we conducted only one split over the dataset. We used decision tree method of the partition model to make a single pass through our dataset to produce a single portioned tree.

b

COVID-19 related deaths per day were reported as mean ± SD values on the partitioned daily cases groups.

c

LogWorth values reported after one split; node splitting is based on the LogWorth statistic; values gives an idea about further splitting on an arm will be done on which variable basis.

d

AICs denote the corrected Akaike’s Information Criteria.

e

Beta outbreak period was considered from the prior month when the Beta variant of SARS-CoV-2 had discovered by scientists in South Africa on December 18, 2020, to March 2021.

f

Percent positivity denotes the percentage of people tested positive for SARS-CoV-2 on a given day.

g

Delta outbreak period was considered from the prior month when the earliest documented sample with Delta variant of SARS-CoV-2 was identified in South Africa (May 08, 2021) to the prior month of the earliest documented sample with Omicron variant of SARS-CoV-2 reported in (November 2021).

h

Omicron outbreak period was considered from the month when the earliest documented sample with Omicron variant was reported in South Africa (November 09, 2021) to the last reported date of this analysis (March 31, 2022).

i

Since January 06, 2022, the Department of Health of the Republic of South Africa had been recorded and reported COVID-19 death backlog as an ongoing audit exercise across the country to address a backlog of COVID-19 mortality.

j

Values are not available for this parameter.