Appropriate training data is a requirement for building good machine-learned models. In this paper, we study the notion of coverage for ordinal and continuous-valued attributes, by formalizing the intuition that the learned model can accurately predict only at data points for which there are "enough" similar data points in the training data set.

Querying a relational database is difficult because it requires users to be familiar with both the SQL language and the schema. However, many users possess enough domain expertise to describe their desired queries by alternative means. For such users, two major alternatives to writing SQL are natural language interfaces (NLIs) and programming-by-example (PBE). Both of these alternatives face certain pitfalls: natural language queries (NLQs) are often ambiguous, even for human interpreters, while current PBE approaches limit functionality to be tractable. Consequently, we propose dual-specification query synthesis, which consumes both a NLQ and an optional PBE-like table sketch query that enables users to express varied levels of domain knowledge. We introduce the novel dual-specification Duoquest system, which leverages guided partial query enumeration to efficiently explore the space of possible queries. We present results from user studies in which Duoquest demonstrates a 62.5% absolute increase in query construction accuracy over a state-of-the-art NLI and comparable accuracy to a PBE system on a limited workload supported by the PBE system. In a simulation study on the Spider benchmark, Duoquest demonstrates a >2x increase in top-1 accuracy over both NLI and PBE.

Data-driven technologies are only as good as the data they work with. On the other hand, data scientists have often limited control on how the data is collected. Failing to contain adequate number of instances from minority (sub)groups, known as population bias, is a major reason for model unfairness and disparate performance across different groups. We demonstrate MithraCoverage, a system for investigating population bias over the intersection of multiple attributes. We use the concept of coverage for identifying intersectional subgroups with inadequate representation in the dataset. MithraCoverage is a web application with an interactive visual interface that allows data scientists to explore the dataset and identify subgroups with poor coverage.

Data analysis impacts virtually every aspect of our society today. Often, this analysis is performed on an existing dataset, possibly collected through a process that the data scientists had limited control over. The existing data analyzed may not include the complete universe, but it is expected to cover the diversity of items in the universe. Lack of adequate coverage in the dataset can result in undesirable outcomes such as biased decisions and algorithmic racism, as well as creating vulnerabilities such as opening up room for adversarial attacks. In this paper, we assess the coverage of a given dataset over multiple categorical attributes. We first provide efficient techniques for traversing the combinatorial explosion of value combinations to identify any regions of attribute space not adequately covered by the data. Then, we determine the least amount of additional data that must be obtained to resolve this lack of adequate coverage. We confirm the value of our proposal through both theoretical analyses and comprehensive experiments on real data.

Data transformation is a critical first step in modern data analysis: before any analysis can be done, data from a variety of sources must be wrangled into a uniform format that is amenable to the intended analysis and analytical software package. This data transformation task is tedious, time-consuming, and often requires programming skills beyond the expertise of data analysts. In this paper, we develop a technique to synthesize data transformation programs by example, reducing this burden by allowing the analyst to describe the transformation with a small input-output example pair, without being concerned with the transformation steps required to get there. We implemented our technique in a system, FOOFAH, that efficiently searches the space of possible data transformation operations to generate a program that will perform the desired transformation. We experimentally show that data transformation programs can be created quickly with FOOFAH for a wide variety of cases, with 60% less user effort than the well-known WRANGLER system.

Advancements in new data analysis and visualization technologies have resulted in wide applicability of data-driven decision making. However, raw data from various sources must be wrangled into a suitable form before they are processed by the downstream data tools. People traditionally write data transformation programs to automate this process, and such work is cumbersome and tedious.

Service-oriented Architecture (SOA) comprises a number of loosely-coupled independent services, which collaborate, interact and share data to accomplish incoming requests. A service invocation can involve multiple services, where each service accesses, processes and shares the client's data. These interactions may share data with unauthorized services and violate client's privacy. The client has no means of identifying if a violation occurred because it has no control over the service invocations beyond its trust domain. Such interactions introduce new security challenges which are not present in traditional systems. This paper proposes a data-centric approach for privacy preserving access control in SOA. Benefits of the proposed approach include the ability to dynamically define access polices by the clients and control data access at the time of each service interaction. A realistic healthcare scenario is used to evaluate the implementation of the proposed solution which validates its viability.

The rise of the mobile-cloud computing paradigm in recent years has enabled mobile devices with processing power and battery life limitations to achieve complex tasks in real-time. While mobile-cloud computing is promising to overcome the limitations of mobile devices for real-time computing, the lack of frameworks compatible with standard technologies and techniques for dynamic performance estimation and program component relocation makes it harder to adopt mobile-cloud computing at large. Most of the available frameworks rely on strong assumptions such as the availability of a full clone of the application code and negligible execution time in the cloud. In this paper, we present a dynamic computation offloading model for mobile-cloud computing, based on autonomous agents. Our approach does not impose any requirements on the cloud platform other than providing isolated execution containers, and it alleviates the management burden of offloaded code by the mobile platform using stateful, autonomous application partitions. We also investigate the effects of different cloud runtime environment conditions on the performance of mobile-cloud computing, and present a simple and low-overhead dynamic make span estimation model integrated into autonomous agents to enhance them with self-performance evaluation in addition to self-cloning capabilities. The proposed performance profiling model is used in conjunction with a cloud resource optimization scheme to ensure optimal performance. Experiments with two mobile applications demonstrate the effectiveness of the proposed approach for high-performance mobile-cloud computing.