GET NON-ZERO RESULTS USING STDEV FOR CERTAIN NUMBERS
Hi,
I get some non-zero results when using Microsoft Excel 97 to caluclate Standard Deviation for the following numbers having the same set of numbers: 1) 4.8, 4.8, 4.8 = Stdev(4.8,4.8,4.8) = 8.43E-08 2) 0.71, 0.71, 0.71 =Stdev(0.71,0.71,0.71) =1.05E-08 3) 0.815, 0.815, 0.815 = dtdev(0.815,0.815,0.815) =1.05E-08 Theoretically, for same set of numbers, the Std deviation should be 0 but when using the Excel to compute Stdev, I discover this is not true for all the numbers (eg see above). Any solution to ensure that when using the Excel to compute Stdev for the set with all same numbers will always return a zero? Regards |
Hi
for an explanation see: http://cpearson.com/excel/rounding.htm As solution use =ROUND(STDEV(...),2) "Non-zero return for Stdev" wrote: Hi, I get some non-zero results when using Microsoft Excel 97 to caluclate Standard Deviation for the following numbers having the same set of numbers: 1) 4.8, 4.8, 4.8 = Stdev(4.8,4.8,4.8) = 8.43E-08 2) 0.71, 0.71, 0.71 =Stdev(0.71,0.71,0.71) =1.05E-08 3) 0.815, 0.815, 0.815 = dtdev(0.815,0.815,0.815) =1.05E-08 Theoretically, for same set of numbers, the Std deviation should be 0 but when using the Excel to compute Stdev, I discover this is not true for all the numbers (eg see above). Any solution to ensure that when using the Excel to compute Stdev for the set with all same numbers will always return a zero? Regards |
Hi
LOOKS LIKE SOME SORT OF ROUNDING ISSUE - I get this whenever I use a population which has more than one decimal place of precision. |
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