Shen et al. (2021) investigate the impact of the COVID-19 lockdown on criminal incidents in Japan between April and May, 2020, employing two empirical approaches, the difference-in-differences (DID) and event study approaches, where they set the start of the incidence (treatment) to April. They find that the COVID-19 lockdown reduced violent and property crime by 12.7% and 20.9%, respectively.

Shen et al. provide a timely analysis of an important research question, and has at least two important contributions in the literature. First, this is the first study on the impact of COVID-19 on criminal incidents in the Japanese context. COVID-19 and the associated mitigation policies had an enormous influence on society, affecting a wide range of areas, including the economy, politics, culture, and crime. Timely assessments of the impact on crime have an important implication for designing further public policy responses to infectious disease pandemics. The impact of COVID-19 differs across countries, and each government adopted different policy measures. It is thus essential to evaluate the impact in various countries.

Second, there is an extensive literature on the socio-economic determinants of crime, and Shen et al. add an important insight to this prior research. Prior studies show that various economic variables affect one's decision to commit a crime, including risk preference, income, opportunity costs, and unemployment (Brosnan, 2018). Shen et al. argue that the voluntary lockdown in Japan positively affected the demand side of crime through various direct and indirect channels. This indicates that COVID-19 would affect different types of crimes differently. Consistent with the theoretical explanations, Shen et al.'s empirical results show that the magnitude and statistical significance of the impact of the COVID-19 lockdown on crime differs according to the type of crime; the largest impact is on breaking-and-entering and there is no significant change in homicide.

One of their interesting findings is the heterogeneous impact of COVID-19 by age group on criminal incidents, showing young individuals are the most effected. There would be two other potentially interesting differences in the impact: heterogeneity by region and by gender. The data used in the analysis is Hanzai Tokei (Crime Statistics), which reports the number of criminal incidents by prefecture. I hypothesize that the crime impacts could differ by the number of COVID-19 cases, with a greater impact in prefectures with more cases, as people are more likely to engage in precautionary behavior, including social distancing. Analyzing the impact using prefecture-level panel data sets would provide useful insights to understand the mechanisms and to obtain policy implications, particularly, given the differences in the timing of the state of emergency declarations across prefectures. In addition, utilizing human mobility data from mobile phones is becoming common in COVID-19-related analyses. Using such data would provide a detailed picture of the relationship between social distancing policies and crimes.

Furthermore, it is well documented that the effect of COVID-19 differs by gender (Alon et al., 2020), which may result in a difference in crime rates. Given the finding of a decrease in sexual assaults, exploring the impact by gender may provide additional useful evidence to inform public policy to strengthen targeted interventions.

One important remark is that Shen et al. assess the short-term impact rather than the medium- to long-term impact of COVID-19 on crime. The impact could differ in the medium- to long-term, as the prolonged impact of the COVID-19 pandemic affected individuals and society differently than it did in the initial phase of the pandemic. In particular, one of the indirect channels of the reduction in crime incidents, the mental health channel, may be different given the reported increase in the suicide rate in the second wave of the pandemic (Tanaka & Okamoto, 2021). Finally, we should note that the analysis is based on police data, which are subject to under- or non-reporting of specific types of crimes, such as serious assaults occurring at home (Boman & Gallupe, 2020; Leslie & Wilson, 2020).

沉等人。( 2021 ) 调查了 COVID-19 封锁对 2020 年 4 月至 5 月期间日本犯罪事件的影响，采用了两种实证方法，即差异中的差异 (DID) 和事件研究方法，并以此为起点发病（治疗）至4月。他们发现，COVID-19 封锁将暴力犯罪和财产犯罪分别减少了 12.7% 和 20.9%。

沉等人。提供对重要研究问题的及时分析，并且在文献中至少有两个重要贡献。首先，这是关于 COVID-19 在日本背景下对犯罪事件的影响的第一项研究。COVID-19 和相关的缓解政策对社会产生了巨大影响，影响了广泛的领域，包括经济、政治、文化和犯罪。及时评估对犯罪的影响对于设计应对传染病大流行的进一步公共政策具有重要意义。COVID-19 的影响因国家而异，各国政府采取了不同的政策措施。因此，必须评估在不同国家的影响。

其次，有大量关于犯罪的社会经济决定因素的文献，Shen等人。为这项先前的研究添加重要的见解。先前的研究表明，各种经济变量会影响一个人的犯罪决定，包括风险偏好、收入、机会成本和失业（Brosnan，  2018 年）。沉等人。认为日本的自愿封锁通过各种直接和间接渠道对犯罪的需求方产生了积极影响。这表明 COVID-19 会对不同类型的犯罪产生不同的影响。与理论解释一致，Shen等. 的实证结果表明，COVID-19 封锁对犯罪的影响程度和统计显着性因犯罪类型而异；最大的影响是破门而入，凶杀案没有显着变化。

他们有趣的发现之一是 COVID-19 按年龄组对犯罪事件的不同影响，表明年轻人受到的影响最大。影响方面还有另外两个潜在的有趣差异：地区和性别的异质性。分析中使用的数据是Hanzai Tokei（犯罪统计)，按县报告犯罪事件的数量。我假设犯罪影响可能因 COVID-19 案件的数量而异，对案件较多的县影响更大，因为人们更有可能采取预防行为，包括保持社交距离。使用地级面板数据集分析影响将为理解机制和获得政策影响提供有用的见解，特别是考虑到各县宣布紧急状态的时间不同。此外，在 COVID-19 相关分析中，利用来自手机的人类移动数据变得越来越普遍。使用这些数据可以详细了解社会疏远政策与犯罪之间的关系。

此外，有充分证据表明 COVID-19 的影响因性别而异（Alon等人，2020 年），这可能导致犯罪率不同。鉴于性侵犯减少的发现，探索性别的影响可能会提供额外的有用证据，为公共政策提供信息，以加强有针对性的干预措施。

一个重要的评论是沉等人。评估 COVID-19 对犯罪的短期影响而不是中长期影响。中长期影响可能会有所不同，因为 COVID-19 大流行的长期影响对个人和社会的影响与大流行初期不同。尤其是减少犯罪事件的间接渠道之一，心理健康渠道，可能会有所不同，因为据报道第二波大流行的自杀率有所上升（Tanaka & Okamoto，  2021 年）。最后，我们应该注意到，该分析基于警方数据，这些数据可能会被漏报或不报特定类型的犯罪，例如在家中发生的严重袭击事件（Boman & Gallupe，  2020 年）; 莱斯利和威尔逊，  2020 年）。