The interquartile range A) is the 50^th percentile score in a data set. B) contains as few as 25% of scores or as many as 75% of scores in a data set C) contains the middle 50% of scores in a data set. D) is the same as the range.

Question

Quizplus · Accepted Answer

The interquartile range (IQR) is defined as the difference between the upper quartile (Q3) and the lower quartile (Q1). Quartiles divide a data set into four equal parts: Q1 represents the 25th percentile, Q2 is the median or 50th percentile, and Q3 represents the 75th percentile. Therefore, the IQR contains the middle 50% of scores in a data set. Option A is incorrect because it is describing the definition of a specific percentile score, not the IQR. Option B is incorrect because the IQR can only contain the middle 50% of scores, never less or more. Option D is incorrect because the range is defined as the difference between the maximum and minimum values in a data set, which is not related to quartiles.

The Interquartile Range