SOAN 2120 Lecture : SOAN 2120 Mar.23.docx
29 Mar 2012
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Document Summary
A measure of dispersion of a set of data around the mean. Variance equals the average of the sum of all the squared deviations of the sample. Deviation of the distance from any single measure of a set to the mean of that set. Compare the deviation from the mean for every measurement in the sample. Average the squared deviations by dividing the sum by the number of measurements in the population [n] Take the square root of the resulting value. **the standard deviation is the square root of the variance** 1792 1666 1362 1614 1460 1867 1439 add them all up and divide by 7 =1600 take each observation [1792, 1666, 1362 etc. ] 1439-1600=-161 square each of these and add them = 214, 870 variance = 214, 870 / 7 =30, 695. 71 standard deviation= 30, 695. 71=175. 20 calories. Extreme scores affect the range the most, however standard deviation can be also affected.
