Articles

Michael Mey, Managing Consultant at Obvious Works, holds a diploma in Computer Science from Furtwangen University, Germany, where he first explored AI and neural networks. With extensive experience in international software projects, particularly in the financial industry, Michael has held key roles at major corporations and launched a crypto startup through an incubation program, blending corporate and entrepreneurial insights. An Agile coach and trainer, he specializes in Requirements Engineering and AI integration. Michael is engaged in the IREB Special Interest Group AI and regularly speaks at conferences like REConf, REFSQ, and Scrum Day. As co-creator of the AIxRE Masterclass, he is dedicated to helping organizations optimize their processes by integrating AI into Requirements Engineering practices.

• AI Assistants in Requirements Engineering | Part 1

Nuno Santos is currently a Senior Business Analyst at Natixis Portugal. He holds a PhD in Technologies and Information Systems, and is also certified from Agile Alliance as CSPO, and from the IIBA as CCBA, AAC and POA. He has also written articles about requirements, agility and product ownership at RE Magazine, BA Digest, Analyst Catalyst, Medium, and in several scientific conferences.

• Requirements Elicitation in Modern Product Discovery
• Inputs to requirements engineering in agile projects

Gareth is an experienced business analyst and product owner who has been working in the telecoms and other industries for longer than he’d like to be specific about. He has been an active member of IREB for some years and is a co-author and examiner within the RE@Agile working group. He lives and works in Germany having successfully escaped from a small, slightly uncooperative island.

• Splitting Requirements at Scale
• RE in Agile Projects: Survey Results
• RE in Agile Projects: a Survey
• How agile can Requirements Engineers really be?

Prof. Dr. Salinesi is an active academic who teaches topics in relation with software design such as Requirements Engineering, and Software Product Lines. He was involved in many funded research projects (FP4, FP5, H2020, ANR) and was the leader for collaborations and consultancy works for various companies such as France Télécom, SNCF, Renault, EDF or REXEL). He has been General Chair of SPLC, CAiSE, REFSQ international conferences, and was Organizing Chair of the 13th IEEE International Conference on Requirements Engineering.

At IREB, Prof Salinesi has acted for 2 mandates as Second Chair of the Executive Committee. He is now Full Member, member of the Editorial Board, and WG Member.

• Conversation with an Artificial Intelligence

Thorsten von Ramsch is Director Engineering at QAULITEST Group. He is an IREB Certified Requirements Engineer, ISTQB Certified Tester Full Advanced Level, ASQF Project Manager, Professional Scrum Master and iNTCCM Certified Professional for Configuration Management. His focus is on the banking and insurance sector, which he advises in the areas of requirements elicitation, test management and test analysis.

• Classical requirements and test analysis a discontinued model?

Gil Regev has been a researcher at EPFL since 1997 in the fields of enterprise information systems, requirements engineering, change management and knowledge management. Since 2008 he is also manager and consultant at Itecor, a boutique consultancy firm. Previously Gil developed software for computer peripherals at Logitech, in Switzerland and California.

• A General Systems Thinking Perspective on the CPRE

Alain Wegmann is a full professor at the School of Computer and Communication Sciences, EPFL, Switzerland. He worked 14 years for Logitech (Switzerland, Taiwan, US) in positions ranging from software developer, IS manager, manufacturing engineering to VP of engineering and OEM marketing before joining the EPFL in 1997. His teaching, consulting and research are in the fields of enterprise architecture, requirements engineering and service engineering.

• A General Systems Thinking Perspective on the CPRE

Olivier Hayard has been a consultant and in charge of IT and Knowledge Management at Itecor, a boutique consultancy firm, since 1993. Olivier’s main interests are business analysis and requirements management, as practitioner, trainer and researcher.

• A General Systems Thinking Perspective on the CPRE

Gildas PREMEL-CABIC works as a Business Analyst at Capgemini (France). Gildas holds the IREB CPRE foundation level certificate. His business domain is the use of simulation for Defence activities. His main domain of interest concerns system modeling and simulation.

• Discovering System Requirements through SysML

Nuno Santos is currently a Senior Business Analyst at Natixis Portugal. He holds a PhD in Technologies and Information Systems, and is also certified from Agile Alliance as CSPO, and from the IIBA as CCBA, AAC and POA. He has also written articles about requirements, agility and product ownership at RE Magazine, BA Digest, Analyst Catalyst, Medium, and in several scientific conferences.

• Inputs to requirements engineering in agile projects

Nuno Ferreira is currently the head of research at i2S Insurance Knowledge, invited professor at ISEP of Porto's Polytechnique Institute and researcher at ALGORITMI research center of Minho’s University in Portugal. He holds a PhD in Software Engineering. He has a strong background in software engineering, project management and process management. His re-search interests are requirements elicitation, process-to-product transitions, logical architectures derivation, and process maturity models.

• Inputs to requirements engineering in agile projects

Ricardo J. Machado is a full professor of Information Systems Engineering and Technology in the Dept. of Information Systems at the University of Minho (UMinho), School of Engineering. Within the Information Systems Engineering domain, his primary research interests are in modelling and requirements for systems analysis and design and in process and project management life-cycles. He has supervised 50 completed PhD and MSc theses in these areas. He has published over 150 scientific publications and 4 industrial patents, and has acted as coordinator (PI) and senior researcher of over 50 R&D projects. Currently, at UMinho he is the vice-rector for institutional development, the director of the ALGORITMI Research Centre, the scientific coordinator of the EPMQ Laboratory at the CCG/ZGDV Institute, the director of the Doctoral Program in Advanced Engineering Systems for Industry, and member of the Board of the UM-Cities Platform.

• Inputs to requirements engineering in agile projects

Project manager since 2008, certified Scrum Product Owner, Agile Project Manager, with foundations of PRINCE2. Over six years of experience as a UX designer and researcher. Worked in digital agencies as a digital project manager, then switched to the client's side. Head of Product in iTaxi, then in Pergamin (e-signature). Worked also for libraries and museums in Poland to help improve the accessibility of digital products.

Awarded by Innovation Ad Award for the prototype for Sensodyne and by nomination in Mobile Trends for the mobile app for drivers. An author of articles about product management, user experience, and accessibility.

• The Potential of User Tests for Requirements Engineering

Luisa Mich is an Associate Professor of Computer Science at the University of Trento, Italy. Her research interests include requirements engineering, creativity and web strategies. She is an author of more than 150 papers.
 

• Interview with John Mylopoulos
• Requirements Elicitation (ReqElic) in My Company

Suzanne Robertson is having a stellar career in information technology and systems engineering. Suzanne is a pioneer in adapting ideas from other domains for automated solutions. She has collaborated in workshops using experts from fields as diverse as modern music, visualization, and cookery. Ideas from these domains were adapted to make major breakthroughs in creative ideas for domains ranging from air traffic control to local government. She is co-author of the best-selling Mastering the Requirements Process, among other books and courses. She is co-creator of the Volere requirements techniques. She was the founding editor of the Requirements Column in IEEE Software.

• Integrating Business Events into your Agile Framework
• How Will It Work?

As a principal and founder of The Atlantic Systems Guild, James Robertson is known for his work in implementing systems engineering principles that link business specialists with solution specialists. James is a consultant, lecturer, author, project leader whose area of concern is the requirements for software, and the contribution that good business analysis makes to successful projects. James is co-author of 5 books that have been influential in the business analysis world. His training as an architect has led to his work on good design principles and to his focus on how innovation can be integrated with business analysis.

• Integrating Business Events into your Agile Framework
• How Will It Work?

Rana Siadati is currently a PhD student in Software Requirements Engineering and also a visiting lecturer by the School of Computer Science at the University of Hertfordshire. Alongside these roles, Rana has many years of academic and industrial experience, also at managerial level, gained in the UK and abroad.

• Learning from history: The case of Software Requirements Engineering

Paul Wernick is a Senior Lecturer in Computer Science at the University of Hertfordshire. Dr Wernick has taken leading roles in the ProSim series of software process simulation workshops, and the IEEE Workshop on Software Evolvability. Dr Wernick’s current research interests cover the high-level human environment within which software processes occur and their simulation, and computer security.

• Learning from history: The case of Software Requirements Engineering

Vito Veneziano is a Senior Lecturer in Computer Science at the University of Hertfordshire, and his interests range from software engineering, HCI, requirements analysis and system modelling, to how software systems impact on organisations. Previously Dr Veneziano worked in IT and project management, business application development, software design and consultancy.

• Learning from history: The case of Software Requirements Engineering

Andreas Maier studied Computational Linguistics, Language Science and Technology and Philosophy at Saarland University in Saarbrücken, Germany. From November 2008 to April 2018, he worked as scientific assistant at Fraunhofer IESE, where he focused on the elicitation and the automatic analysis of user requirements provided in natural language. In May 2019, he finished his PhD in computer science, where he investigated difficulties in the identification and specification of hedonic quality in user requirements and developed possible solutions for the mitigation of these difficulties.

• ReqInspector

Simon Darting studied applied computer science with focus on communication at the University of Applied Sciences in Worms, Germany. Subsequent to his studies he started working as a researcher at Fraunhofer IESE in 2012, where he focused on requirements- and systems engineering within large-scale projects. In 2017 he completed his Master's degree in "Software Engineering for Embedded Systems" at the Technical University of Kaiserslautern, Germany. Since December 2018, he has been employed at BASF SE in Advanced Business Analytics with a focus on predictive maintenance.

• ReqInspector

Priyank Arora is a Senior Business Analyst working in the digital IT space for 12+ years. He is a CBAP certified professional with a Core Credential in Business Analytics from Harvard Business School. He works on large scale digital transformation projects for the world’s leading travel group, where he helped to transition the requirement engineering processes from traditional to Agile working methodologies. He was also involved with a machine learning initiative within his organisation and is a data science enthusiast with an interest in applying analytical thinking and decision automation for business growth.

• Data Science – the expanding frontier for Business Analysts

Dr. Michael Jastram is an expert model-based systems engineering (MBSE), with a focus on requirements. He has over 20 years experience in software development and requirements engineering, which he regularly shares as author and public speaker. Amongst other things, he publishes weekly updates on Systems Engineering Trends [German] and monthly updates on Requirements Engineering [English].

Michael is a leader in open source requirements management, being project lead of the Eclipse Requirements Modeling Framework. He is also a strong advocate of open standard and actively contributes to the OMG Requirements Interchange Format (ReqIF).

Today, he is founder and principal systems engineer of Formal Mind GmbH, a service provider in Open Systems Engineering.

You can connect digitally with Michael via his Blog [en] | Blog [de] | Twitter | LinkedIn | Xing.

• Modeling Requirements with Constraints

Andreas Kara has 15 years experience as IT project manager in leading positions, both representing customer and contractor. As a trainer, he helps his students to become successful project managers and to enjoy their profession. As a coach, he provides intense knowledge transfer on the job.

• Modeling Requirements with Constraints

Bastian Tenbergen is an Assistant Professor for Computer Science at the State University of New York at Oswego. He has co-authored articles and contributed to several books in the area of Software Engineering. Bastian’s main research focus is on Model-Based Requirements Engineering, Context Analysis, and Safety of Embedded and Cyber-Physical Systems. He has many years of project and consulting experience and has worked closely with industry.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Andreas Vogelsang is a post-doc researcher in the software & systems engineering group at the Technical University of Munich. He works on model-based requirements engineering and participated in several research collaborations with industrial partners especially from the automotive industry. His research published was published in relevant international conferences like RE, REFSQ, or ICSE.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Thorsten Weyer is a research group leader at the University of Duisburg-Essen. He has been a member of organization committees, program committees and reviewer for scientific conferences and journals. Thorsten gives regular lectures at the University and is an experienced conference speaker. He has also held several leading positions in research projects and technology transfer projects. He is member of the IREB council and head of the IREB working group Requirements Modeling.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Andreas Froese works as a research assistant in the working group Software Systems Engineering (Prof. Dr. Klaus Pohl) at the University of Duisburg-Essen. He worked in several research projects where he was able to expand his knowledge in the domain of Requirements Engineering for software-intensive Embedded Systems, as well as in those of model-based Context Analysis and context-based Quality Assurance.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Jan Christoph Wehrstedt works as a mathematician at the Technology Field Automation & Control at Siemens Corporate Technology. Currently he is Senior Key Expert for Efficient Simulation Driven System Development. He is the project manager of several business (Siemens internal) and public funded projects dealing with the integration of simulation and modeling approaches towards a simulation based engineering of technical systems and plants and it’s embedding into PLM lifecycle and tools.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Veronika Brandstetter is a mathematician in the Technology Field Automation & Control at Siemens Corporate Technology. She is developing methods for seamless engineering and improved operation of technical systems based on simulation. Recently, she focused on simulation based design for manufacturing technologies. She has been working in various Siemens internal research projects as well as in publicly funded projects also managing part of them in different groups within the Technology Field.

• Modeling Requirements and Context as a means for Automated Requirements Validation

Eduard C. Groen is engineering psychologist. His fascination with the rapid rise of man-machine interfaces and other changes that affect society inspires him to contribute with technologies that optimally make use of the potential that these developments bring. As Fraunhofer IESE operates at the intersection of science and industry, he is involved in a variety of projects, while leading the development of the “Crowd-based Requirements Engineering” approach.

• How Requirements Engineering can benefit from crowds

Matthias Koch studied computer science with a focus on software engineering. Since 2012, he is employed as engineer at Fraunhofer IESE and mainly addresses the topics of requirements engineering and business analysis. In this context, he was involved in research projects on the pre-project and requirements definition phase, case studies and product evaluations. In research as well as industry projects, he regularly acts as requirements responsible, conducts workshops with customers and provides consulting.

• How Requirements Engineering can benefit from crowds

(born 1971) in Hannover teaches requirements engineering for more than 10 years at the Hochschule Hannover (University of applied sciences and arts, Hannover, Germany) he is visiting professor at Frankfurt School of Finance and Management.
Besides the academic qualification Lars holds certificates at IREB CPRE foundation level and is a member of the IREB Advance modeling group. In addition to that he holds the PMI P.M.P. (Project Management Professional) and A.C.P. (Agile Certified Practitioner) certification.
Lars Baumann has more than 20 years of experience in the field of international project management, and requirements engineering trainings. He actively works as a consultant for many clients in Germany and internationally.

Contact: Hochschule Hannover – Fakultät IV Wirtschaft und Informatik
Mail: Lars.Baumann@hs-hannover.de

• Requirements Engineering Workshop in Mozambique

(Born 1997) a student at the KKS Hannover, uses Java, C and C++ and is currently managing projects such as the development of a computer game using the Unreal Engine 4, building and programming an Arduino-Robot. In addition to that he is a voluntary member in VDini supporting scientific projects with young students.
Furthermore he spent a year abroad in New Zealand in 2013, where he went to the Te-Puke High School. He is a voluntary tutor for refugees from Syria and did voluntary work at the Struwig National Resort next to Kruger Park in South-Africa.

Contact : Henrik_Baumann@hotmail.com

• Requirements Engineering Workshop in Mozambique

Martin Tate is an IT consultant who has now personally run or rescued 52 projects to select off-the-shelf solutions, interviewed over 725 people to capture the requirements for selections and appraised over 1,000 candidate solutions. A ‘poacher turned gamekeeper’, he formerly worked for an IT provider and was trained to sell software. BCS, The Chartered Institute for IT, made him a Chartered Fellow for eminence in evaluating software and recently published his book, a practitioner guide to procuring off-the-shelf IT.

• IT Requirements when Buying, not Making

Dr. Christof Ebert is managing director at Vector Consulting Services. He supports clients around the world to improve product strategy and product development and to manage organizational changes. A trusted advisor for companies around the world, member of industry boards, he lectures at the Universities of Stuttgart and at the Sorbonne in Paris. He authored several books including the popular “Systematic Requirements Engineering”. Contact him at christof.ebert@vector.com

• Cyber Security Requirements Engineering
• Product Management

Stefan Meier is passionate about exploring and experimenting with new Requirements Engineering practices and methodologies. He many years of practical experience as Project Manager, Requirements Engineer  and Agile Coach. He loves talking to different stakeholders and sharpening their ideas and visions to get a crisp and clear understanding of their needs and values. 
He works at SPF Consulting and currently helps customers switching their requirements frameworks from waterfall processes towards agile approaches like Scrum. Additionally he is an conversant trainer for IREB CPRE FL, Visual Facilitation and Agile Requirements.

• Applying IREB RE practices in an agile environment

Ariè Avnur is a veteran software developer, manager and executive, with over 40 years of experience developing software of various types, from real-time embedded and control systems through enterprise, web applications, to health IT systems. Ariè accompanied software engineering methodologies and requirements engineering since the 70’s, published papers and developed tools for the trade. Recently he was involved in the introduction and development of RE practice for Scrum projects in a major European healthcare company. Arie’s current interests include the application of RE and development methods for better software development, healthcare IT and Internet of Things platforms.

• A Finite State Machine Model for Requirements Engineering

Pascal Roques is a senior consultant and trainer who has been modeling for more than twenty five years in various domains. He began with SADT and OMT, then moved to UML (OCUP Advanced Certification) and RUP in Valtech, where he was in charge of the Modeling part of the training catalog. Pascal is now working on his own at PRFC [www.prfc.fr], mainly in the field of Systems Modeling with SysML. He is also co-founder of SysML France association, and published several books on UML and SysML in French.

• Modeling Requirements with SysML

Albert Tort is the Research&Innovation Solutions Lead in Sogeti Spain. During the last years, he has been working as Quality Assurance and Software Control & Testing specialist in several projects for customers in different sectors (banking, airlines, insurance, procurement, etc.). Furthermore, he has been the lead of research&innovation projects developed at Sogeti. He was the winner of the “Capgemini-Sogeti Testing Innovation Awards 2015” for the submission of the best individual entry "Recover: Reverse Modeling and Up-To-Date Evolution of Functional Requirements in Alignment with Tests. He is also a member of the SogetiLabs community.

Previously, he served as a professor and researcher at the Services and Information Systems Engineering Department of the Universitat Politècnica de Catalunya-Barcelona Tech. As a member of the Information Modeling and Processing (MPI) research group, he focused his research on conceptual modeling, software engineering methodologies, OMG standards, knowledge management, requirements engineering, service science, semantic web and software quality assurance. Currently, he is also the coordinator of the postgraduate degree in Software Quality Assurance of the School of Professional & Executive Development of the Technical University Of Catalunya (BarcelonaTech).

He obtained his Computer Science degree in 2008 and he received his M.Sc. in Computing in 2009. In 2012 he presented the PhD thesis “Testing and Test-Driven Development of Conceptual Schemas”. He is the author of several publications in software engineering journals and conferences.

• KCycle: Knowledge-Based & Agile Software Quality Assurance
• The Recover Approach

Hans van Loenhoud MSc is a consultant and teacher at Taraxacum in the Netherlands. He has been working in software development for more than 35 years, starting as a Cobol programmer and later on specialized in test and quality management.
In this role, he has been teaching various ISTQB test courses and has been chair of TestNet, the Dutch association of professional software testers. In recent years, he joined IREB to build a bridge between software testing and requirements engineering. He gives various Business Analysis, Requirements Engineering and Software Testing trainings. Hans is also a lecturer at the Amsterdam University of Applied Sciences for these topics and participates in the IREB advanced level Elicitation working group.

• On the right track
• The goal is to solve the problem
• Translating Exam Questions

Johan Zandhuis is Product manager at SYSQA BV, an organisation specialised in quality assurance in IT. The themes ‘creating value with IT’ and ‘getting grip on IT’ play a constant role when he’s doing the job. “Why are we doing this” is a question he likes to ask. Besides other publications Johan is co-author of the Dutch book ‘Grip op requirements’ based on the IREB syllabus. Also he is one of the initiators for the Dutch translation of the IREB-dictionary and the IREB foundation syllabus. Contact: jzandhuis@sysqa.nl

• Poor requirements?

Brett Bicknell is an engineer at Critical Software Technologies and has played a key role in a number of formal methods initiatives, including the FP7 ADVANCE project. His software engineering experience encompasses varying levels of criticality and verification and validation activities. His previous work includes embedded systems, solutions for data acquisition and analysis, and a number of European-funded R&D ventures. He holds a BSc degree in Physics.

• Advance
• Rigorous Verification

Karim Kanso has worked within the field of formal methods and software engineering for many years, on various projects in the domains of transportation and aerospace. He has received a PhD in theoretical computer science, and is actively interested in the question of how requirement engineering can be applied to new disciplines, such as autonomous system engineering? He is currently working on the ADVANCE programme at Critical Software Technologies.

• Advance
• Rigorous Verification

Brett Bicknell is an engineer at Critical Software Technologies and has played a key role in a number of formal methods initiatives, including the FP7 ADVANCE project. His software engineering experience encompasses varying levels of criticality and verification and validation activities. His previous work includes embedded systems, solutions for data acquisition and analysis, and a number of European-funded R&D ventures. He holds a BSc degree in Physics.

• Rigorous Verification

Karim Kanso has worked within the field of formal methods and software engineering for many years, on various projects in the domains of transportation and aerospace. He has received a PhD in theoretical computer science, and is actively interested in the question of how requirement engineering can be applied to new disciplines, such as autonomous system engineering? He is currently working on the ADVANCE programme at Critical Software Technologies.

• Rigorous Verification

Daniel McLeod has worked on a variety of imaging sensor systems in the Airborne, Land and Naval domains. His previous work includes algorithm development, system design, requirements analysis and verification and project management. He is currently working within the smart energy domain on a Low Voltage monitoring system and a system for automated control of low voltage transformers in response to customer demand and distributed generation.

• Rigorous Verification

Harry M. Sneed has a Master’s Degree in Information Sciences from the University of Maryland, 1969. He has been working in the IT field since 1967 when he started as a FORTRAN programmer for the US Navy Department. He migrated to Germany in 1971 and worked first for the Federal University Administration and then for Siemens in the database area. In 1978 he set up the first commercial software test laboratory in Budapest. There he developed the first German requirements engineering tool SoftSpec in 1982. That tool was used to document the requirements in many large German organizations, including BMW, Bertelsmann, Thyssen Steel and the German Railways. That tool was used not only to collect and store the requirements on the mainframe, but also to check the completeness and consistency of the requirements, as well as to generate a system design.

At the end of the 1980’s Sneed moved over to the field of reverse and reengineering and became involved in projects throughout Europe. In 2009 he received the Stevens Award from the IEEE Computer Society for his pioneering achievements in that field. He conducts courses at two technical colleges and two universities. He has published over 400 technical articles and written 23 books on the subjects of software testing, maintenance, migration and measurement. His work in requirement engineering is mainly in connection with reverse engineering, change management and test, three areas in which he still works as freelance consultant.

• Tracing Change Requests
• Automated Quality Assurance

Having finished her diploma in quantum optics Maria-Therese Teichmann couldn’t resist meeting the complex challenges of Information Technology. For fifteen years she has been working at Software Daten Service GmbH as a business analyst and quality manager in banking software. Her focus there are long term quality decisions, which nowadays are more and more difficult to argue against business interests. Besides the business job she loves to work at the University of Applied Sciences Technikum Wien, was part of a gender project and offers classes in software evolution, relational databases and Software Engineering topics.

• Gender Studies

Eva Gebetsroither works as a Senior Technical Translator in the localisation team of Software Daten Service GmbH. Apart from translations and terminology management she is responsible for language quality assurance. Within the framework of her field of activity there are numerous connections to Requirements Engineering. As an expert in the area of languages and communication she focuses on the role of natural language in Requirements Engineering.

• Gender Studies

After graduating in Communication Science with a focus on public relations and corporate communications in Salzburg and Shanghai, Corinna Unterfurtner finished the MBA in General Management with a focus on coaching, training and education. Corinna collected practical experience as a project manager at the University of Salzburg. Now she is responsible for project and requirements management, the training of new customers and support requests at an ERP business software for SME. Additionally she supports customers in process optimization and workflow design with the help of HELIUM V.

• Gender Studies

Alexandra Kreuzeder is the project manager of "ditact women's IT summer studies", that is part of the ICT&S Center of the University of Salzburg. She graduated at the University of Vienna in Sociology in 1997. Focusing on the processes of socialization, she started in 1998 a year-long research project concerning the gender socialization processes of girls and boys in kinder gardens in Copenhagen, Denmark. Returning to Salzburg in August 1999 she worked in the field of Internet Technology and was project manager of the ditact_women's IT summer university. From March 2011-November 2012 she took a time out to build up her own company "Salzburg Coaching" that offers communication and stress reduction training. Since last year she has shared the management of the ditact summer university with Carina Bachinger from the ICT&S Center.

• Gender Studies