Statistics and Data (Algebraic)

The Five-Number Summary The Five-Number Summary gives us a measure of the spread of the data, which tells us how widely distributed or highly variable the data are. Range = maximum value – minimum value. The range can be strongly influenced by outliers. Quartiles separate the data into fourths. Q1 (the first quartile) is the median of the lower half of the data; Q2 (the second quartile) is the median of all of the data; Q3 (the third quartile) is the median of the upper half of the data. Interquartile Range (IQR) is the spread between the first and third quartiles. Q3 – Q1 = IQR Five Number Summary: {minimum, Q1, median, Q3, maximum} Outlier - a number is a data set that is more than 1.5 ∙ IQR below the first quartile or above the third quartile.