Inaug.-diss.--Halle-Wittenberg. / Lebenslauf. "Literatur": p. [115]-116.

In this thesis I investigate whether two clear and simple indicators, dividends and franking credits, provide users with useful information to assess earnings persistence. Persistence is an important attribute of earnings (Dechow and Schrand 2004). I argue and show earnings persistence is a function of firm life-cycle. Firms can generally be divided into three life stages: establishing profitability, sustainable profitability and declining profitability. Using a simple one-period persistence model I demonstrate that dividends and higher franking credits identify firms in the different stages of the life-cycle. Dividends provide an inherent signal of firms that are in the mature phase of the life-cycle, and hence provide information about earnings persistence. I show firms that pay dividends have persistent profits and losses that reverse. However dividend paying firms are not homogenous. Firms that pay franked dividends have significantly more persistent earnings than firms that pay unfranked dividends. Consistent with higher franking credits identifying more mature firms, fully franked dividend paying firms have significantly less persistent losses than partially franked dividend paying firms. Importantly, my primary results provide an alternative explanation to Hanlon (2005) and add to our understanding of the accrual anomaly. Both Hanlon and my study investigate the informativeness of tax on earnings persistence. I demonstrate that firms that have large differences between the level of franking and accounting income (i.e., pay unfranked dividends while reporting a profit) have large book-tax differences. Such differences in tax and accounting income are a function of the firm life-cycle. Large book-tax differences are not necessarily the result of opportunism (or earnings management). Thus firms with large book-tax differences are typically establishing profitability or entering the declining phase. These firms have less persistence profits, accruals and cash flows than firms with small book-tax differences. I conclude the accrual anomaly is a function of inherent firm characteristics associated with different phases of the life-cycle rather than being a function of earnings management.

My research investigates three questions: How do we customize protocols and implementations to account for the unique requirement of each setting and its target community, what are necessary steps that we can take to transition secure computation tools into practice, and how can we promote their adoption for users at large? In this dissertation I present several of my works that address these three questions with a particular focus on one of them. First my work on "Hecate: Abuse Reporting in Secure Messengers with Sealed Sender" designs a customized protocol to protect people from abuse and surveillance in online end to end encrypted messaging. Our key insight is to add pre-processing to asymmetric message franking, where the moderating entity can generate batches of tokens per user during off-peak hours that can later be deposited when reporting abuse. This thesis then demonstrates that by carefully tailoring our cryptographic protocols for real world use cases, we can achieve orders of magnitude improvements over prior works with minimal assumptions over the resources available to people. Second, my work on "Batched Differentially Private Information Retrieval" contributes a novel Private Information Retrieval (PIR) protocol called DP-PIR that is designed to provide high throughput at high query rates. It does so by pushing all public key operations into an offline stage, batching queries from multiple clients via techniques similar to mixnets, and maintain differential privacy guarantees over the access patterns of the database. Finally, I provide three case studies showing that we cannot hope to further the adoption of cryptographic tools in practice without collaborating with the very people we are trying to protect. I discuss a pilot deployment of secure multi-party computation (MPC) that I have done with the Department of Education, deployments of MPC I have done for the Boston Women’s Workforce Council and the Greater Boston Chamber of Commerce, and ongoing work in developing tool chain support for MPC via an automated resource estimation tool called Carousels.