QMS 102 Lecture Notes - Lecture 6: Box Plot, Interquartile Range, Quartile

• School: Ryerson University
• Department: Quantitative Methods
• Course: QMS 102
• Professor: Nursel Ruzgar

Document Summary

Quartiles split the ranked data into 4 segments with an equal number of values per segment. The first quartile, q1, is the value for which 25% of the observations are smaller and 75% are larger. Q2 is the same as the median (50% of the observations are smaller and 50% are larger) Only 25% of the observations are greater than the third quartile. Find a quartile by determining the value in the appropriate position in the ranked data, where. Ranked value (n is the number of observed values) The iqr is q3 q1and measures the spread in the middle 50% of the data. The iqr is also called the midspread because it covers the middle 50% of the data. The iqr is a measure of variability that is not influenced by outliers or extreme values. Measures like q1, q3, and iqr that are not influenced by outliers are called resistant measures.