An Epidemic of Uncertainty is a multicourse gourmet meal for demographers. It is a book to settle into, chew on, and ruminate over with good friends. Empirically dense, theoretically rich, and analytically smart, the book moves the reader effortlessly between sophisticated quantitative analyses and everyday village and town life in and around Balaka, Malawi. And it brings demography, in all its interdisciplinary and conceptual splendor, to bear on the new subfield, Jenny Trinitapoli, the book's author, wants to usher in: Uncertainty Demography. The book examines how a generation of Malawian youth, who have lived their entire lives under the shadow of a severe HIV and AIDS epidemic, are transitioning to adulthood and navigating the stuff of life—beginning and ending relationships, having children, and for some, getting and living with HIV, and dying—from AIDS or giving birth or lightning strikes, among other causes of death.

The book is based on an extraordinary and groundbreaking dataset, Tsologo La Thanzi (TLT: Healthy Futures in Chichewa), codesigned and led by Trinitapoli and her close collaborator Sara Yeatman. The impetus for the study was the observation that in Malawi, as in several other African countries, first sex, first marriage, and first birth unfold over a two-year period. Yet most major African surveys, most notably the Demographic and Health Surveys, collect cross-sectional data every five years, limiting analyses of the transition to adulthood. TLT (https://tsogololathanzi.uchicago.edu/, which is publicly available) is a longitudinal survey following respondents—young women and their male partners—over a 10-year period, from ages 15–25 to ages 25–35. The core survey included eight waves of data collected between 2009 and 2011, with each wave collected every four months. There was some attrition from the original sample—1505 respondents in 2009, to 1200 respondents in 2015 (80 percent of the original sample) to 1022 respondents in 2019 (68 percent) (p. 51). This led to a refresher sample collection in 2012 and 2019. Finally, there was follow-up data collection in 2015 and 2019. The survey, described in Chapter 2, is not just exceptional in its intensity but also in its creativity and methodological ambition. Data collection methods ranged from a standard survey questionnaire to biomarker data collection involving pregnancy and HIV testing, to card sorts, cognition tests, relationship scripts, literacy tests, vignettes, personal fieldnotes, first- and second-hand ethnographic observations, and a primary method for measuring uncertainty—bean counts. (Respondents could place up to 10 beans corresponding to their assessment of the probability of different event occurrences).

At the heart of the book is the argument that individual uncertainty, and how people make sense of it, has consequences for their subsequent actions, and further that individual uncertainty aggregates and works as a powerful social force and a major driver of demographic change at a population level. The case of Balaka is instructive: the HIV epidemic unfolded in a context with a plethora of other major and more immediate life uncertainties around livelihood, food insecurity, and morbidity and mortality from other causes. Taking uncertainty as a starting point, Trinitapoli turns standard “don't know” responses to survey questions on their head, showing how not knowing can drive population-level outcomes. She demonstrates this through measuring uncertainty and then examining responses and outcomes in subsequent surveys. Perhaps the biggest claim in the book is that uncertainty can be a more important driver of social action than certainty. For Malawian youth, the book convincingly shows, it accelerates life course transitions—into marriage, divorce, and parenthood—powering a “relationship churning” that puts them at risk of HIV acquisition and transmission as they move through the marriage regime. The book is convincing in making the case that not understanding uncertainty about a phenomenon of interest—the “don't knows” or the “known unknowns”—can lead to misunderstanding the phenomenon of interest, and missing the consequential ways it is shaping individual and population-level dynamics.

In the case of HIV uncertainty, described in Chapters 4 and 5, for example, Trinitapoli finds that nearly 40 percent of young people in the study are uncertain about their HIV status. Further, over the life of the study, she found not only that people move in and out of periods of uncertainty (as opposed to a permanent “worrier class,” p. 103), but that fully half the sample had experienced “acute uncertainty” (defined as —four to six beans, on a 1–10 scale), at different points in time, despite a 14 percent HIV prevalence in Balaka. In other words, the HIV uncertainty epidemic was bigger than the HIV epidemic. Trinitapoli found no effect of access to very frequent testing (every four months over more than two years for a sample of participants) on population-level uncertainty. Ironically, only testing positive led to HIV-related certainty. HIV uncertainty was also demographically consequential. Following the participants over time, she found it led to accelerated childbearing, and that increasing uncertainty was associated with significantly worse self-rated health, more sick days, and more depression. Indeed she concludes, HIV uncertainty, not just positivity, is “a clinically relevant condition”(p. 221).

HIV uncertainty arose from relationship uncertainty, examined in Chapters 6 and 7. Balaka features universal marriage (95 percent of young women married at least once over the study period), and almost 40 percent were divorced and/or remarried one or more times (pp. 138–139). Each relationship transition carried increased HIV risk—from 2012 on, over 20 percent of divorced and remarried women were living with HIV, more than twice that of women in their first marriage (p. 141). Relationship churning was driven by a high level of mistrust, suspicion, and anxiety around their partner's fidelity. And this was amplified by the fear of HIV acquisition and widespread cell phone use—users were more suspicious of their partners than nonusers. In Chapter 8, Trinitapoli then considers the larger “mortality landscape,” placing HIV/AIDS into context. The chapter examines the interaction between large-scale mortality declines in infant and adult mortality, and everyday perceptions of death, the so-called “drumbeat of funerals” at the individual, family, and village level. Almost half (44 percent) of the TLT sample had lost a sibling by 2019, and throughout the study period, participants attended at least one funeral a month. In the 2019 survey round, 40 percent attended two or more funerals a month (p. 190). Thus, despite population-level mortality declines, in daily life, mortality remained a major source of uncertainty for young people.

In this and other chapters, the book makes an important case for taking seriously “population chatter” or the significance of on the ground perceptions of demographic events; by weaving back and forth between accounts of everyday episodes and survey findings, it shows how consequential they are for young people's life course transition decisions and trajectories. Much of the population chatter in the book came from ethnographic observations written by “Gertrude.” We know that she is Malawian, an “extraordinary research assistant,” and that she has a good memory, but we are also told that “Gertrude's private life is not on display here” (p. 45). There is an ethical dimension here, which is well taken, but the reader is also left with several questions. What culture or social class did she come from? For example, I was surprised that she did not already know that she needed to carry a wrap just in case she had to cover herself for a funeral (p. 192)—was this practice unique to this ethnic group, was mortality lower where she came from? What did she find familiar or strange about Balaka? What did villagers think she was there to do? And how did she decide what to write about each day? Knowing this would help readers better understand the eyes through which they are viewing and coming to understand Balaka. More broadly, readers might wonder, how were the fieldnotes analyzed? What was the analytic process used to masterfully weave the various data components into the book? A methodological supplement engaging some of these questions would have further enriched this book's contribution.

Readers interested in pursuing uncertainty demography will be helped by Chapter 3, which engages in a rich, though largely uncritical, literature review of previous demographic work on uncertainty and offers a working definition of the phenomenon and subfield. The chapter is less clear, however, on where the frontiers of this field are, how this project in particular is located within that literature, and what questions or gaps are left for future demographers to take up. This book will surely launch a thousand ships. I hope Trinitapoli plans a companion article as a guide for others.

Finally, the policy implications of the book are immense. In Chapter 9, the book discusses ending problematic programs like conditional cash transfers to incentivize hospital births, better tests to eliminate the uncertainty period after HIV testing, doing more to end livelihood uncertainty, and “taming the mortality landscape” (p. 222) in order to reduce uncertainty in people's lives. However, if we take the book's arguments seriously—that relationship uncertainty underlies HIV uncertainty; that in fact there can be an “epidemic of uncertainty”; and that population-level changes, such as mortality reduction, do not necessarily filter down to population chatter or individual perceptions in a way that can translate to certainty—how then do we “treat” and create policy around uncertainty?

Overall, An Epidemic of Uncertainty is a tour de force. Its originality, sophistication, creativity, and the groundbreaking nature of the survey on which it was based, make this book an outstanding achievement. I anticipate it becoming a classic on graduate student syllabi and taking up permanent residence on demographers’ bookshelves.

不确定性的流行对于人口统计学家来说是一顿多道菜的美食。这是一本适合与好朋友一起阅读、咀嚼和沉思的书。这本书经验丰富、理论丰富、分析巧妙，让读者毫不费力地在复杂的定量分析和马拉维巴拉卡及其周边地区的日常村庄和城镇生活之间切换。它将人口学，以其跨学科和概念的辉煌，带入新的子领域，该书的作者珍妮·特里尼塔波利（Jenny Trinitapoli）希望引入：不确定性人口学。这本书探讨了马拉维的一代年轻人，他们的一生都生活在严重的艾滋病毒和艾滋病流行的阴影下，他们如何过渡到成年并应对生活中的事情——开始和结束关系、生孩子，以及对某些人来说，感染艾滋病毒并与之共存，以及死于艾滋病、分娩或雷击等死亡原因。

这本书基于一个非凡且具有开创性的数据集 Tsologo La Thanzi（TLT：Chichewa 的健康未来），由 Trinitapoli 和她的亲密合作者 Sara Yeatman 共同设计和领导。这项研究的推动力是观察到，与其他几个非洲国家一样，在马拉维，第一次性行为、第一次婚姻和第一次生育发生在两年的时间里。然而，大多数主要的非洲调查，尤其是人口统计和健康调查，每五年收集一次横截面数据，限制了对成年过渡的分析。TLT（https://tsogololathanzi.uchicago.edu/，公开发布）是一项纵向调查，跟踪对象为年轻女性及其男性伴侣，为期 10 年，年龄范围从 15-25 岁到 25-35 岁。核心调查包括 2009 年至 2011 年间收集的八波数据，每波每四个月收集一次。原始样本有所减少——2009 年有 1505 名受访者，2015 年有 1200 名受访者（占原始样本的 80%），再到 2019 年有 1022 名受访者（占原始样本的 68%）（第 51 页）。这导致了 2012 年和 2019 年的更新样本收集。最后，2015 年和 2019 年进行了后续数据收集。第 2 章中描述的这项调查不仅在强度上非常出色，而且在创造力和方法论雄心方面也非常出色。数据收集方法包括标准调查问卷、涉及妊娠和艾滋病毒检测的生物标志物数据收集、卡片分类、认知测试、关系脚本、读写能力测试、小插曲、个人田野笔记、第一手和二手人种学观察以及主要方法用于测量不确定性——豆子计数。（受访者最多可以根据他们对不同事件发生概率的评估放置 10 个豆子）。

本书的核心论点是，个人的不确定性以及人们如何理解它，会对他们随后的行为产生影响，而且个人的不确定性聚集在一起，成为一股强大的社会力量，成为人口变化的主要驱动力。人口水平。巴拉卡的案例具有启发意义：艾滋病毒流行是在生计、粮食不安全以及其他原因造成的发病率和死亡率等其他重大和更直接的生活不确定性的背景下发生的。以不确定性为出发点，特立尼塔波利将调查问题的标准“不知道”回答转变为他们的头脑，展示了不知道如何推动人口层面的结果。她通过测量不确定性，然后检查后续调查中的反应和结果来证明这一点。也许这本书最大的主张是，不确定性可能是比确定性更重要的社会行动驱动力。这本书令人信服地表明，对于马拉维年轻人来说，它加速了生命历程的转变——结婚、离婚和为人父母——引发“关系搅动”，使他们在婚姻制度中面临感染和传播艾滋病毒的风险。这本书令人信服地证明，不理解感兴趣现象的不确定性（“不知道”或“已知的未知”）可能会导致误解感兴趣的现象，并错过它塑造个人的相应方式。和人口层面的动态。

例如，在第 4 章和第 5 章中描述的 HIV 不确定性的情况下，Trinitapoli 发现研究中近 40% 的年轻人不确定自己的 HIV 状况。此外，在研究的整个过程中，她发现人们不仅会进出不确定时期（而不是永久的“担忧者阶层”，第 103 页），而且整整一半的样本都经历过“严重的不确定性”。 ”（定义为——四到六颗豆子，按 1 到 10 的等级），在不同的时间点，尽管巴拉卡的艾滋病毒感染率为 14%。换句话说，艾滋病毒的不确定性流行比艾滋病毒的流行更严重。Trinitapoli 发现，进行非常频繁的测试（在两年多的时间里每四个月对参与者样本进行一次测试）对人口水平的不确定性没有影响。讽刺的是，只有检测呈阳性才能确定与艾滋病毒相关的情况。艾滋病毒的不确定性在人口统计学上也产生了影响。随着时间的推移，她对参与者进行了跟踪，发现这会导致生育速度加快，而不确定性的增加与自评健康状况显着恶化、病假天数增加和抑郁症增加有关。事实上，她的结论是，艾滋病毒的不确定性，而不仅仅是阳性，是“一种临床相关状况”（第 221 页）。

HIV 的不确定性源于关系的不确定性，这在第 6 章和第 7 章中进行了研究。Balaka 的特点是普遍婚姻（95% 的年轻女性在研究期间至少结过一次婚），近 40% 的女性离婚和/或再婚一次或多次（pp . 138–139）。每次关系转变都会增加艾滋病毒风险——从 2012 年起，超过 20% 的离婚和再婚女性感染艾滋病毒，是第一次婚姻女性的两倍多（第 141 页）。关系的破裂是由于对伴侣忠诚度的高度不信任、怀疑和焦虑造成的。对感染艾滋病毒的恐惧和手机的广泛使用进一步加剧了这种恐惧——用户比非用户更怀疑自己的伴侣。在第八章中，特立尼塔波利考虑了更大的“死亡率格局”，将艾滋病毒/艾滋病置于背景之下。本章探讨了婴儿和成人死亡率的大规模下降与个人、家庭和村庄层面对死亡的日常看法（即所谓的“葬礼鼓声”）之间的相互作用。到 2019 年，近一半（44%）的 TLT 样本失去了兄弟姐妹，在整个研究期间，参与者每月至少参加一次葬礼。在 2019 年的调查中，40% 的人每月参加两次或两次以上葬礼（第 190 页）。因此，尽管人口死亡率下降，但在日常生活中，死亡率仍然是年轻人不确定性的主要来源。

在本章和其他章节中，本书提出了认真对待“人口闲谈”或对人口事件的实地看法的重要性的重要案例；通过在日常事件和调查结果之间来回穿梭，它显示了它们对年轻人的生命历程转变决策和轨迹有多么重要。书中的大部分人口话题都来自“格特鲁德”所写的民族志观察。我们知道她是马拉维人，是一位“非凡的研究助理”，并且她有很好的记忆力，但我们也被告知“格特鲁德的私生活不在这里展示”（第45页）。这里有一个道德维度，这一点很好理解，但也给读者留下了几个问题。她来自什么文化或社会阶层？例如，令我惊讶的是，她并不知道她需要携带裹布，以防万一她必须在葬礼上遮盖自己（第 192 页）——这种做法是这个种族群体独有的吗？来自？她对巴拉卡有哪些熟悉或陌生的地方？村民们认为她来这里是做什么的？她是如何决定每天写什么的？了解这一点将有助于读者更好地理解他们正在观看并理解巴拉卡的眼睛。更广泛地说，读者可能想知道，现场笔记是如何分析的？用于巧妙地将各种数据组件编织到书中的分析过程是什么？涉及其中一些问题的方法论补充将进一步丰富本书的贡献。

对研究不确定性人口统计学感兴趣的读者将受益于第三章，该章对先前关于不确定性的人口学研究进行了丰富但基本上不加批判的文献回顾，并提供了该现象和子领域的工作定义。然而，这一章不太清楚该领域的前沿在哪里，该项目在文献中的位置，以及未来人口统计学家需要解决的问题或空白。这本书肯定会发射一千艘船。我希望 Trinitapoli 计划撰写一篇配套文章作为其他人的指南。

最后，这本书的政策影响是巨大的。在第 9 章中，本书讨论了结束有问题的计划，例如有条件现金转移支付以激励医院分娩、更好的测试以消除艾滋病毒检测后的不确定期、采取更多措施消除生计的不确定性以及“控制死亡率”（第 222 页）。以减少人们生活中的不确定性。然而，如果我们认真对待这本书的论点——关系的不确定性是艾滋病毒不确定性的基础；事实上，可能存在“不确定性流行病”；而且人口水平的变化，例如死亡率的降低，并不一定会转化为人口的喋喋不休或个人看法，从而转化为确定性——那么我们如何“对待”不确定性并制定政策呢？

总的来说，《不确定性的流行》是一部杰作。其独创性、复杂性、创造性以及其所依据的调查的开创性，使本书成为一项杰出的成就。我预计它会成为研究生教学大纲中的经典，并永久保留在人口学家的书架上。