weightsd

# weightsd - RELATED COMMANDS MEAN = Compute the mean of a...

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WEIGHTED STANDARD DEVIATION Statistics LET Subcommands 2-66 September 3, 1996 DATAPLOT Reference Manual WEIGHTED STANDARD DEVIATION PURPOSE Compute the weighted standard deviation of a variable. DESCRIPTION The formula for the standard deviation is: (EQ 2-21) while the formula for the weighted standard deviation is: (EQ 2-22) where w i is the weight for the ith observation, N’ is the number of non-zero weights, and x w is the weighted mean of the observations. An error message is printed if a negative weight is encountered. Weighted standard deviations are often used for frequency data. SYNTAX LET <par> = WEIGHTED STANDARD DEVIATION <y> <weights><SUBSET/EXCEPT/FOR qualiﬁcation> where <y> is a response variable; <weights> is a variable containing the weights; <par> is a parameter where the weighted standard deviation is saved; and where the <SUBSET/EXCEPT/FOR qualiﬁcation> is optional. EXAMPLES LET STANDARD DEVIATION = WEIGHTED MEAN Y1 WEIGHT LET STANDARD DEVIATION = WEIGHTED MEAN Y1 WEIGHT SUBSET TAG > 2 DEFAULT None SYNONYMS None

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Unformatted text preview: RELATED COMMANDS MEAN = Compute the mean of a variable. MEDIAN = Compute the median of a variable. STANDARD DEVIATION = Compute the standard deviation of a variable. VARIANCE = Compute the variance of a variable. WEIGHTED MEAN = Compute the weighted mean of a variable. WEIGHTED VARIANCE = Compute the weighted variance of a variable. APPLICATIONS Data Analysis IMPLEMENTATION DATE 94/11 (there was an error in the computation for earlier versions) s x i x ( 29 2 i 1 = N N 1 ------------------------------= sd w w i x i x w ( 29 2 i 1 = N N' 1 ( 29 w i i 1 = N N'--------------------------------------------------------------------------= Statistics LET Subcommands WEIGHTED STANDARD DEVIATION DATAPLOT Reference Manual September 3, 1996 2-67 PROGRAM LET Y = DATA 2 3 5 7 11 13 17 19 23 LET W = DATA 1 1 0 0 4 1 2 1 0 LET A = STANDARD DEVIATION Y LET AW = WEIGHTED STANDARD DEVIATION Y W PRINT A AW The values of A and AW are 7.46 and 5.82 respectively....
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## This note was uploaded on 10/30/2010 for the course MP 200 taught by Professor Guna during the Fall '10 term at Duke.

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weightsd - RELATED COMMANDS MEAN = Compute the mean of a...

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