Research and Development by
Itsuki Noda, AIST
Corresponding Research Area
Simulation and designing countermeasures against possible COVID-19 resurgence: predicting spreading of infection, estimating and verifying the effectiveness of countermeasures, and predicting deman
Summary
- Transportation data during Jan.-Oct., 2020 can be represented as a mixture of 12 basic patterns.
- Each basic pattern is a combination of the following spacial and temporal patterns.
- Spacial: “among neighbor prefectures” and “between metropolitan and nation-wide areas”.
- Temporal: “weekday” and “holiday”.
- Each basic pattern is a combination of the following spacial and temporal patterns.
- Correlation analysis between weekly average of effective reproduction number (Rt) and the 12 basic patterns after mid. of March tells:
- Rt of Hokkaido has week correlation with 3 basic patterns.
- Need simulation analysis to confirm dependency and controllability.
- Rt of Hokkaido has week correlation with 3 basic patterns.
Procedure of Analysis
- Consider travel data among prefectures as a 3D tensor whose axes are origin, destination, and date.
- Data source: Blogwatcher, Inc.
- Inner-prefecture travel are not counted, because they include staying home.
- The travel tensor is normalized as a probability tensor whose total is 1.
- Apply non-negative tensor factorization to the travel tensor and get a mixture of basic patterns.
- Each basic pattern is a direct product of an inter-prefecture matrix (spacial factor) and a day vector (temporal pattern).
- Each basic pattern is a direct product of an inter-prefecture matrix (spacial factor) and a day vector (temporal pattern).
- Calculate correlation between changes of Rt and the day vector of each basic pattern.
BIC Analysis
- Try to calculate BIC in order to determine the suitable number of basic patterns.
- BIC becomes minimum at 12 basic patterns.
Acquired Temporal Pattern of Each Basic Patterns (1)
- Plots of changes of probabilities of temporal patterns of 12 basic patterns (0th...11th).
- The 0th pattern (among neighbor prefectures, weekday) is a major part of whole travel pattern.
Acquired Temporal Pattern of Each Basic Patterns (2)
- Details of 1st ... 11th basic patterns.
- The 4th and 7th patterns are relatively large.
- The 4th pattern: among neighbor prefecture, holiday.
- The 7th pattern: between metropolis and nation-wide.
- The 4th and 7th patterns are relatively large.
Each Temporal Patterns (0th ... 5th)
- types:
- weekday: has narrow valleys at weekends.
- holiday: has peeks at weekends.
- pre-corona: Jan. and Feb. are larger than summer and autumn
- post-corona: summer and autumn are larger than Jan. and Feb.
- horizontal axis: day
- Jan. 1st -- Oct. 30th, 2020.
- vertical axis: prob.
Each Temporal Patterns (6th ... 11th)
- types:
- weekday: has narrow valleys at weekends.
- holiday: has peeks at weekends.
- pre-corona: Jan. and Feb. are larger than summer and autumn
- post-corona: summer and autumn are larger than Jan. and Feb.
- horizontal axis: day
- Jan. 1st -- Oct. 30th, 2020.
- vertical axis: prob.
Each Spacial Pattern(0th-5th)
- lneighbor type: large at diagonal region.
- metropolis nation-wide: horizontal and vertical bands.
- nation-wide: spread widely.
- horizontal: from pref.
- vertical: to pref.
- color: prob. (scaled for each pattern)
Each Spacial Pattern(6th-11th)
- lneighbor type: large at diagonal region.
- metropolis nation-wide: horizontal and vertical bands.
- nation-wide: spread widely.
- horizontal: from pref.
- vertical: to pref.
- color: prob. (scaled for each pattern)
Prefectures
- 0: Hokkaido (representative of Hokkaido Area)
- 1: Aomori
- 2: Iwate
- 3: Miyagi (representative of Tohoku Area)
- 4: Akita
- 5: Yamagata
- 6: Fukushima
- 7: Ibaraki
- 8: Tochigi
- 9: Gunma
- 10: Saitama
- 11: Chiba
- 12: Tokyo (representative of Kanto Area)
- 13: Kanagawa
- 14: Yamanashi
- 15: Nagano
- 16: Niigata
- 17: Toyama
- 18: Ishikawa (representative of Hokuriku Area)
- 19: Fukui
- 20: Gifu
- 21: Shizuoka
- 22: Aichi (representative of Tokai Area)
- 23: Mie
- 24: Shiga
- 25: Kyoto
- 26: Osaka (representative of Kinki Area)
- 27: Hyogo
- 28: Nara
- 29: Wakayama
- 30: Tottori
- 31: Shimane
- 32: Okayama
- 33: Hiroshima(representative of Chugoku Area)
- 34: Tokushima
- 35: Kagawa
- 36: Ehime (representative of Shikoku Area)
- 37: Kochi
- 38: Yamaguchi
- 39: Fukuoka (representative of North Kyushu Area)
- 40: Saga
- 41: Nagasaki
- 42: Kumamoto
- 43: Oita
- 44: Miyazaki
- 45: Kagoshima (representative of South Kyushu Area)
- 46: Okinawa (representative of Okinawa Area)
Correlation Matrix between Basic Patterns and Rt.
- Period: mid of Mar. 〜 Oct.
- Use weekly average of Rt with 8 days delay.
- Rt of Hokkaido has week correlations with f03, f06 and f07 patterns.
- Each pattern is between metropolis and nation-wide on weekday.
Scatter Plot
Scatter of f06(horizontal) and Rt(vertical)
Scatter of f07(horizontal) and Rt(vertical)
- Scatter Plots between Rt of Hokkaido and f06, f07
- week correlations
- colors indicate the number of week.
- The correlation with f06 becomes weeker in later weeks.
(ref.) Correlation Matrix between Basic Patterns and Rt.
- using Rt on-time (no delay)
- correlations are relatively low.