Which of the following statements is true about the variability of datasets?

The statement regarding extreme scores increasing variability is accurate because extreme scores, often referred to as outliers, can have a significant impact on the spread of a dataset. Variability is a measure of how much the data points deviate from the mean or median, and when extreme values are introduced, they can widen the range, increase the standard deviation, and lead to a higher interquartile range. This means that datasets with extreme scores will show greater variability when compared to those without them.

Understanding extreme scores in the context of data analysis is crucial, as they can influence statistical conclusions. For example, in psychological research, outliers might represent significant cases that warrant further investigation or could be due to measurement error or unique circumstances.

In contrast, the concept that standard deviation or interquartile range could decrease variability misrepresents the function of these measures, as they are tools used to quantify the existing variability in the dataset. Similarly, the range, while useful in reporting the spread, does not eliminate variability; rather, it provides a measure of how spread out the data is.