Rens's research arranged by topic

On this page you can find more information about the projects Rens is working on.

Note that we are still updating information about the sub-projects.

Small Samples

Researchers often have difficulties collecting enough data to obtain statistical power: when target groups are small (e.g., children with severe burn injuries), hard to access (e.g., infants of drug-dependent mothers), or measuring the participants requires prohibitive costs (e.g., measuring phonological difficulties of babies). Such obstacles to collecting data usually leads to a limited data set. Researchers can overcome this through simplifying their hypotheses and statistical models. However, this strategy is undesirable since the intended research question cannot be answered in this way.


Individuals can be conceptualized as a hierarchical system of individuals nested within groups. Such systems can be observed at different ‘levels’, and variables explaining differences between individuals and/or groups may be defined at each level. This leads to research generally referred to as ‘multilevel research’.

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