Freiburg Mindfulness Inventory (FMI) Short Form and Revised Form (FMI-13R) ­­— Norm Scores and Psychometrics in a Representative German Sample

Abstract Background The Freiburg Mindfulness Inventory (FMI) in its short form is one of the most frequently used instruments in research to measure self-attributed mindfulness. We sought to calibrate it in a representative German sample and to replicate its psychometric properties. Methods We administered the FMI-14 to a representative German sample. We revisited the psychometric analysis and calculated a Confirmatory Factor Analysis (CFA). To gauge external validity of the instrument, we also presented the FMI together with four items of the Patient Health Questionnaire (PHQ4). Results We recruited 1,021 respondents from a commercial online panel and approximated a representative sample of the German population. The best psychometric properties are obtained with a revised version of the FMI-13R, where the only negatively coded item was removed due to lack of fit. McDonald’s Omega was found to be 0.88 and the mean item-scale intercorrelation was 0.36. The construct is unidimensional, with two highly correlated sub-constructs, Presence and Acceptance (r = 0.64), which can be separated for conceptual reasons if desired. The CFA supported this model. Age and gender stratified norm scores were calculated and reported. Regression analyses and partial correlation analyses showed negative correlation of mindfulness and measures of anxiety and depression, as expected, and thereby support our previous findings that the instrument is valid and that the health conveying effects component is the Acceptance component of mindfulness. Conclusion The FMI-13R is a psychometrically sound and valid instrument for the assessment of mindfulness. Norm scores can now be used by clinicians and researchers to classify individuals or samples into a range of values compared to the German population.