MAT 2377 Lecture Notes - Lecture 8: Percentile, Multimodal Distribution, John Tukey
9 May 2014
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In these notes, we learn tech- niques to describe the data. Data : we will denote the n observations of the random variable x as x1, x2, . Example 1 : the following n = 8 measurements (in millimeters) were made on the inside diameter of forged piston rings used in an automobile engine. Hence, x1 = 74. 001, x2 = 74. 003, . Note : we will describe the central tendencies or the location of the distribution of these measurements with the sample mean and the sample median. The sample mean is the dened as the average of the n values and it is denoted x. In our example, we get (cid:80)n x = i=1 xi n. Percentile : a percentile is a value among 99 values that divide the sample into 100 (approximately) equal parts in the sense that about 1% of the values are in the class.
