spreiding

Spreiding, in Dutch usage, refers to the spread or dispersion of a quantity within a dataset or phenomenon. It describes how far individual values diverge from each other or from a central tendency, such as the mean or median. Spreiding is a separate concept from central tendency, which summarizes where the values are concentrated.

In statistics, spreiding is quantified by several measures. The range (bereik) is the difference between the maximum and minimum values. The interquartile range (IQR) measures the spread of the middle 50 percent of values. Variance (variantie) and standard deviation (standaardafwijking) capture average squared or square-root deviations from the mean. The mean absolute deviation (MAD) and the median absolute deviation offer robust alternatives less sensitive to outliers. The coefficient of variation expresses spreiding relative to the mean, useful for comparing variability across datasets with different scales. Most formulas distinguish between population and sample versions.

Spreiding is essential for interpreting data credibility, comparing datasets, and informing models and decisions. A dataset with small spreiding implies consistency and predictability, while large spreiding indicates greater variability and uncertainty. Visual tools such as histograms and box plots help convey spreiding at a glance, highlighting outliers and the overall distribution shape. The relationship between spreiding and distribution characteristics like skewness and kurtosis matters: two datasets can share a similar mean but differ markedly in spread or in shape.

In application, spreiding informs risk assessment, quality control, experimental reproducibility, and financial analysis, where the width of a distribution translates into potential gains or losses.