In a research study, the term that describes the difference between the smallest and largest observation is called the:

The term that describes the difference between the smallest and largest observation in a set of data is known as the range. The range provides a simple numeric measure of the spread of values in a dataset. To calculate the range, you subtract the smallest observation (minimum value) from the largest observation (maximum value).

This metric is fundamental in statistics as it gives a sense of the variability or dispersion in the data. It can help researchers understand how data points are distributed and is particularly valuable in descriptive statistics when summarizing data sets.

In contrast, standard deviation measures the average distance of each data point from the mean, and first degree of freedom relates to the number of values in the final calculation that are free to vary, which is more relevant in the context of variance and hypothesis testing. Absolute value refers to the magnitude of a number regardless of its sign, which does not apply to the measurement of range in this context.