这是中国和意大利covid-19疫情致死率差异的一个奇怪案例。
据我所知，病死率是某种疾病的死亡人数与被诊断患有该疾病的受试者总数之比。
从这个假设出发，我试图分析中国/意大利疫情之间的死亡率差异。在这里，我提出了一个可重现的 R 示例来探索这个变量：
# Import dataset from authoritative source:
# https://ourworldindata.org/coronavirus-source-data
covid <- read.csv("https://covid.ourworldindata.org/data/ecdc/full_data.csv")
# Subsetting only data from China and Italy
dataset <- subset(covid, location == "China" | location == "Italy")
# Fatality ratio: is the proportion of deaths from a certain disease compared to the
# total number of people diagnosed with the disease for a certain period of time.
dataset$fatality <- round(dataset$total_deaths/dataset$total_cases*100, 2)
# Outbreak duration in days
dataset$days <- difftime(dataset$date,min(dataset$date), units="days")
# Generating plot
library(ggplot2)
ggplot(dataset, aes(days, fatality, color = location, group = location))+
geom_smooth(size= .5, alpha=.25, color = "gray65")+
geom_line()+
geom_point()+
labs(x="Outbreak duration (days)", y= "Fatality rate (%)", color = "Location")+
theme_light(14)
EDT：
条形图
# Generating bar plot
library(ggplot2)
ggplot()+
geom_bar(data=subset(dataset, location == "China"),
aes(days, fatality, fill = "China"),
stat = "identity", position = position_dodge(), alpha = .75)+
geom_bar(data=subset(dataset, location == "Italy"),
aes(days, fatality, fill = "Italy"),
stat = "identity", position = position_dodge(), alpha = .75)+
labs(x="Outbreak duration (days)", y= "Fatality rate (%)", fill = "Location")+
scale_fill_brewer(palette = "Set1")+
theme_light(14)
在此基础上，我对所分析的两个国家之间的死亡率差异感到有些困惑。事实上，中国的最高死亡率为 4%，而意大利则超过 6%。出于这个原因，我有两个问题：
我的计算是否正确？
如果是，为什么在死亡率方面有如此巨大的差异？
美国东部时间二
我想改进这个问题，报告最近的一篇科学论文，它可以部分解释这些差异。事实上，Li 等人报告说，对于每个 COVID+ 患者，其他 5-10 名未记录的 COVID+ 导致了误导性的死亡率。此外，正如评论中所报告的，迄今为止，全球范围内还没有明确的诊断方法。
然而，与中国相比，意大利的每日累计死亡人数正在大幅增加：
# Generating bar plot
library(ggplot2)
ggplot()+
geom_bar(data=subset(dataset, location == "China"),
aes(days, new_deaths, fill = "China"),
stat = "identity", position = position_dodge(), alpha = .75)+
geom_bar(data=subset(dataset, location == "Italy"),
aes(days, new_deaths, fill = "Italy"),
stat = "identity", position = position_dodge(), alpha = .75)+
labs(x="Outbreak duration (days)", y= "Daily deaths (n)", fill = "Location")+
scale_fill_brewer(palette = "Set1")+
theme_light(14)
那里发生了什么事！湖北省在地表和人口方面与意大利几乎相似，但在人口平均年龄方面却大不相同，因为意大利是欧盟最古老的国家之一。