Johannes Gärtner

Flexible Working Hours, Health, and Well-Being in Europe: Some Considerations from a SALTSA Project

The project brought together researchers from 9 EU-Countries and resulted in a number of actions, in particular the following: (a) There is an urgent need of defining the concept of flexible working hours, since it has been used in many different and even counterintuitive ways; the most obvious distinction is where the influence over the working hours lies, that is between the “company-based flexibility” and the “individual-oriented flexibility”; (b) The review of the Legislation in force in the 15 European countries shows that the regulation of working times is quite extensive and covers (Council Directive 93/104/EC) almost all the various arrangements of working hours (i.e., part-time, overtime, shift, and night work), but fails to provide for flexibility; (c) According to the data of the Third EU Survey on Working Conditions, longer and “irregular” working hours are in general linked to lower levels of health and well-being; moreover, low (individual) flexibility and high variability of working hours (i.e., company-based flexibility) were consistently associated with poor health and well-being, while low variability combined with high autonomy showed positive effects; (d) Six substudies from different countries demonstrated that flexible working hours vary according to country, economic sector, social status, and gender; overtime is the most frequent form of company-based flexibility but has negative effects on stress, sleep, and social and mental health; individual flexibility alleviates the negative effects of the company-based flexibility on subjective health, safety, and social well-being; (e) The literature review was able to list more than 1,000 references, but it was striking that most of these documents were mainly argumentative with very little empirical data. Thus, one may conclude that there is a large-scale intervention ongoing in our society with almost completely unknown and uncontrolled effects. Consequently, there is a strong need for systematic research and well-controlled actions in order to examine in detail what flexible working hours are considered, what and where are their positive effects, in particular, as concerns autonomy, and what regulation seem most reasonable.

Efficient generation of rotating workforce schedules

Generating high-quality schedules for a rotating workforce is a critical task in all situations where a certain staffing level must be guaranteed, such as in industrial plants or police departments. Results from ergonomics (BEST, Guidelines for shiftworkers, Bulletin of European Time Studies No. 3, European Foundation for the Improvement of Living and Working Conditions, 1991) indicate that rotating workforce schedules have a profound impact on the health and satisfaction of employees as well as on their performance at work. Moreover, rotating workforce schedules must satisfy legal requirements and should also meet the objectives of the employing organization. In this paper, our description of a solution to this problem is being stated. One of the basic design decisions was to aim at high-quality schedules for realistically sized problems obtained rather quickly, while maintaining human control. The interaction between the decision-maker and the algorithm therefore consists of four steps: (1) choosing a set of lengths of work blocks (a work block is a sequence of consecutive days of work), (2) choosing a particular sequence of blocks of work and days-off blocks amongst these that have optimal weekend characteristics, (3) enumerating possible shift sequences for the chosen work blocks subject to shift change constraints and bounds on sequences of shifts, and (4) assignment of shift sequences to work blocks while fulfilling the staffing requirements. The combination of constraint satisfaction and problem-oriented intelligent backtracking algorithms in each of the four steps allows for finding good solutions for real-world problems in acceptable time. Computational results from a benchmark example found in the literature confirmed the viability of our approach. The algorithms have been implemented in commercial shift scheduling software.

A Taxonomy of Dirty Time-Oriented Data

Data quality is a vital topic for business analytics in order to gain accurate insight and make correct decisions in many data-intensive industries. Albeit systematic approaches to categorize, detect, and avoid data quality problems exist, the special characteristics of time-oriented data are hardly considered. However, time is an important data dimension with distinct characteristics which affords special consideration in the context of dirty data. Building upon existing taxonomies of general data quality problems, we address ‘dirty’ time-oriented data, i.e., time-oriented data with potential quality problems. In particular, we investigated empirically derived problems that emerge with different types of time-oriented data (e.g., time points, time intervals) and provide various examples of quality problems of time-oriented data. By providing categorized information related to existing taxonomies, we establish a basis for further research in the field of dirty time-oriented data, and for the formulation of essential quality checks when preprocessing time-oriented data.

Hierarchical Temporal Patterns and Interactive Aggregated Views for Pixel-Based Visualizations

Many real-world problems involve time-oriented data. Time data is different from other kinds of data--explicitly harnessing the structures of time in visualizations can guide and support users’ visual analysis processes. State-of-the-art visualizations hardly take advantage of the structures of time to aid users in understanding and exploring the data. To bring more flexibility to the analysis process, we have developed interactive visual methods incorporating the structures of time within a pixel-based visualization called GROOVE (granular overview overlay). GROOVE uses different techniques to visualize time-oriented data by overlaying several time granularities in one visualization and provides interactive operators, which utilize the structures of time in different ways to capture and explore time-oriented data.

TimeCleanser: a visual analytics approach for data cleansing of time-oriented data

Poor data quality leads to unreliable results of any kind of data processing and has profound economic impact. Although there are tools to help users with the task of data cleansing, support for dealing with the specifics of time-oriented data is rather poor. However, the time dimension has very specific characteristics which introduce quality problems, that are different from other kinds of data. We present TimeCleanser, an interactive Visual Analytics system to support the task of data cleansing of time-oriented data. In order to help the user to deal with these special characteristics and quality problems, TimeCleanser combines semi-automatic quality checks, visualizations, and directly editable data tables. The evaluation of the TimeCleanser system within a focus group (two target users, one developer, and two Human Computer Interaction experts) shows that (a) our proposed method is suited to detect hidden quality problems of time-oriented data and (b) that it facilitates the complex task of data cleansing.

Participatory Design in Consulting

This article addresses the use of participatory design (PD) techniques in non-research projects from the perspective of consulting. The central categories for analyzing the course of action and the relationship of actors are risks perceived by consultants, customers, and clients. The basis of this article is a large number of consulting projects where participatory techniques were used. Overall it seems feasible to use PD in consulting. Still using PD, especially as a consultant in systems-design, has to be considered risky for both consultants and customers. Therefore techniques that reduce risks are crucial. Several such techniques are well known (steering committee, milestones, prototyping). Some additional, more PD-specific techniques are discussed. The analysis further led to the issues of organizing the technical process and the group process. Both processes are important when using PD in consulting. The technical process assumes responsibility and thereby requires involvement in order to secure contracts. At the same time this conflicts with the group process where neutrality is needed. Therefore, separation of facilitation from design by working in teams of two is considered. This also supports the expertise needed for such projects as it is sometimes difficult to find individuals with both qualifications.

An AI-Based Break-Scheduling System for Supervisory Personnel

Designing shift plans represents a difficult but interesting task because they must satisfy various, often conflicting, requirements. In this article, we address a complex real-world break-scheduling problem for supervisory personnel and present a scheduling system that can help professional planners create high-quality shift plans. Supervisory personnel spend most of their workday in front of computer monitors, addressing critical and constantly changing situations. For employees working under such conditions to always maintain high levels of concentration, its essential that they take occasional breaks. Usually, the amount of break time, as well as the position and duration of breaks within their work time (shift) are regulated by labor rules that must be satisfied by a feasible shift plan. Moreover, to guarantee effective supervision, a minimum number of employees must be working at any given time.

A Comparison of Programming Platforms for Interactive Visualization in Web Browser Based Applications

Recently, Web browser based applications have become very popular in many domains. However, the specific requirements of interactive Information Visualization (InfoVis) applications in terms of graphics performance and interactivity have not yet been investigated systematically in this context. In order to assess browser-based application platforms, we provide a systematic comparison of server-based rendering, Java Applets, Flash, and Silverlight from several points of view. We aim to aid InfoVis developers in choosing the appropriate technology for their needs.

A hybrid LS-CP solver for the shifts and breaks design problem

The problem of designing workforce shifts and break patterns is a relevant employee scheduling problem that arises in many contexts, especially in service industries. The issue is to find a minimum number of shifts, the number of workers assigned to them, and a suitable number of breaks so that the deviation from predetermined workforce requirements is minimized. We tackle this problem by means of a hybrid strategy in the spirit of Large Neighborhood Search, which exploits a set of Local Search operators that resort to a Constraint Programming model for assigning breaks. We test this strategy on a set of random and real life instances employed in the literature.

A Heuristic Based System for Generation of Shifts with Breaks

In this paper a system for the automatic generation of shifts with breaks is presented. The problem of generating shifts with breaks appears in many areas of workforce scheduling, like in airline companies, airports, call centers etc. and is of high practical relevance. A heuristics algorithm for solving this problem is described. It is based on greedy assignment of breaks in shifts and repair steps for finding the best position of breaks inside of shifts. The commercial product in which the algorithms are included is used in practice. Computational results for a real life problem in a large European airport are given.