Staff members of the operation unit Methodology provide advice to all scientific staff at the Institute on questions relating to study design, statistical data analysis, and psychometrics for planning, conducting, analyzing, and publishing scientific projects. We aim at optimizing the methodological quality of scientific work at the Institute.

General and fundamental questions of study design relate to the development of suitable experimental, quasi-experimental, and observational research designs in cross-sectional and longitudinal studies, as well as considerations relating to pros and cons of laboratory based studies in comparison with ambulatory studies that are being conducted in participants’ daily life. Specific aspects of advice relate to the development of hypotheses, power analysis and sample size calculation, research ethics, opportunities and limitations of specific measurement methods, pros and cons of within and between subjects designs, options of controlling systematic and unsystematic confounding variables, and consequences of design decisions for internal and external validity.

In the area of statistical data analysis we provide general advice relating to fundamental questions, as well as in-depth advice relating to more complex issues from all areas of statistical methods and models for all types of outcome variables. This includes, for example, analysis of categorical and forced-choice data, inter-rater reliability, advanced multivariate methods, and all variants of mixed effects regression and structural equation models. With regard to implementation we refer to suitable software solutions and give advice on how to use them.

Relevant areas of psychometric issues relate to planning and development of tests and questionnaires, theoretical and applied aspects of classical test theory and item response theory, as well as general questions on reliability and validity. Specific methods of test development and psychometric analysis can be chosen as needed, and their application can be observed in advisory capacity; examples are exploratory and confirmatory factor analysis, assessment of the reliability of psychometric scales, development of validation hypotheses and designs, measurement invariance analysis, analysis of forced-choice items, or questions on scaling and standardization.

In the context of collaborative projects, the operation unit Methodology provides independent contributions to in-depth discussions, complex applications, or specific and suitable adaptations of statistical models.

In addition, the unit manages a collection of psychometric tests and personality assessment instruments, serves as contact for acquisition suggestions, and provides advice relating to the selection of suitable tests and their adequate administration.