STA 2023 Lecture Notes - Lecture 13: Average Weekly Earnings, Percentile Rank, Standard Deviation
Document Summary
A z-score or standard score for a value is obtained by subtracting the mean from the value and dividing the result by the standard deviation. A z-score represents the number of standard deviations a value is above or below the mean. Percentiles separate the data set into 100 equal groups. A percentile rank of a datum represents the percentage of data values below the datum. The average weekly earnings in dollars for various industries are listed below. Deciles separate the data set into 10 equal groups d1=p10 d4=p40. Quartiles separate the data set into 4 equal parts q1=p25 q2=md q3=p75. An outlier is an extremely high or low data value when compared with the rest of the data values. A data value less than q1-1. 5(iqr) or greater than q3+1. 5(iqr) can be considered an outlier. Using the procedure outlined above, check the data set for outliers. Anything above or below these points is outlier.
