Like many medical studies, the Berlin Aging Study II (BASE·II) is based on a non·random "convenience sample" of self·recruited participants. To study processes of selectivity in BASE·II, we used an identical questionnaire to compare BASE·II with a large, representative reference study, the...

Today, Germany's citizens are happier on average than at any other point in time since reunification. Even though more than 20 years have passed, the average level of happiness in eastern Germany is still significantly lower than that in western Germany. This is demonstrated by the most recent...