STAT 2060 Lecture Notes - Lecture 2: Box Plot, Bias Of An Estimator, Unimodality
29 May 2017
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Document Summary
The most common measures of central tendency are the mean, median, and mode. The mean is the average of all observations. When we are working with a sample, the sample mean is denoted x, where: x/={xi/n (i=1) Example: suppose we have the numbers -2, 4, 8, 13, 19. We can calculate the sample mean as: x={xi/n. X is a sample mean, but it is often used to estimate the population mean, ( mew ). x bar is statistic. The mean uses all data points in its calculations (which is good! ), but is therefore sensitive to extreme values (which is bad!) x bar used to estimate mew. Example: suppose we have the numbers -2, 4, 8, 13, 190. Thus extreme values in data set can result in a mean that is not reflective of most of the data. The median is the middle value when the data is ordered smallest to largest. If n odd, median is the middle value.
