MAT 2379 Lecture Notes - Lecture 1: Biostatistics, Descriptive Statistics, Quartile
15 Dec 2015
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Mat 2379, introduction to biostatistics, lecture notes for chapter section 9. 1 (part 2)1. Suppose we have a quantitative variable x whose observed values are x1, . A statistic is a function of these observed value. Descriptive statistics give a useful summary of the data. The most commonly used descriptive statistics are: the mean and the median, the standard deviation, minimum and maximum values, the quartiles q1, q3, and the interquartile range, measures of center. We will describe the center of the distribution with : (i) the sample mean x is the average of the n observations: If we put a mass of 1/n on each observation xi, then x is the center of the mass. Example 1. (weight) let x be the weight (in kg) of a randomly chosen 12-year girl. The di erence between a data point and its mean is called a deviation. The deviation of the i-th observation is xi x.
