Hello all,
Can anyone tell me how to calculate the coefficient of variation using SPSS? I have searched the help and gone through the different menu options without finding anything. Please let me know if there is additional information I can provide. -Jesse This communication is intended for the use of the recipient to which it is addressed, and may contain confidential, personal and privileged information. Please contact the AADAC ITS Helpdesk at 780-422-2336 immediately if you are not the intended recipient of this communication, and do not copy, distribute, or take action relying on it. Any communication received in error, or subsequent reply, should be deleted from your system. |
I'm surprised enough that nobody's answered this, that I think I must
be missing something. At 03:18 PM 9/28/2006, Jesse Jahrig wrote: >Can anyone tell me how to calculate the coefficient of variation using >SPSS? If, as I understand, you mean simply the standard deviation divided by the mean, then if you want the CV of a single variable across cases, AGGREGATE using functions MEAN and SD, and divide the results; if it's multiple variables in one case, use functions MEAN and SD in the transformation language (in COMPUTE statements), and divide the results. |
Hi Richard and Jesse
RR> I'm surprised enough that nobody's answered this, that I think I must RR> be missing something. It looks that I din't spot that message until you replied... Sorry RR> At 03:18 PM 9/28/2006, Jesse Jahrig wrote: >>Can anyone tell me how to calculate the coefficient of variation using >>SPSS? RR> If, as I understand, you mean simply the standard deviation divided by RR> the mean, then if you want the CV of a single variable across cases, RR> AGGREGATE using functions MEAN and SD, and divide the results; if it's RR> multiple variables in one case, use functions MEAN and SD in the RR> transformation language (in COMPUTE statements), and divide the RR> results. My contribution to the topic (better late than never) If you don't want the CV as a new variable, but simply as a statistic in a pivot table, you can also use RATIO: this procedure computes several statistics for the ratio of two variables, including confidence intervals for the median and coefficient of variation (mean and median centered). To trick RATIO to compute a cv or a median CI for a SINGLE variable (not the ratio of two variables) you just have to compute a variable filled with "1" and use it as denominator. The result will be the CV for the ratio between your variable and 1, and it is evident that any variable divided by 1 remains unchanged. See this example (I have added also the 95%CI for the median, just for didactic purposes), if you don't want it erase "CIN(95) MEDIAN": DATA LIST FREE/dietgroup iron (2 F8). BEGIN DATA 0 83 0 76 0 112 0 113 0 115 0 91 0 101 0 84 0 92 0 73 0 91 0 95 0 107 0 118 0 123 0 96 0 84 0 118 0 122 0 78 0 117 0 103 0 98 0 111 0 130 0 79 0 130 0 126 0 141 0 115 1 75 1 122 1 128 1 88 1 112 1 110 1 106 1 130 1 79 1 131 1 97 1 125 1 102 1 71 1 111 1 132 1 106 1 92 1 108 1 87 1 86 1 87 1 98 1 132 1 94 1 92 1 121 1 86 1 122 1 100 1 108 1 96 1 115 1 114 1 75 1 84 1 98 1 95 1 86 1 78 1 114 1 114 1 101 1 95 1 99 1 96 1 108 1 86 1 97 1 114 END DATA. VAR LABEL dietgroup 'Diet Group'/ iron 'Seric Iron levels (µg/100 ml) '. VALUE LABEL dietgroup 0 'Standard' 1 'Vegetarian'. TEMPORARY. COMPUTE one=1. RATIO STATISTICS iron WITH one BY dietgroup /PRINT = CIN(95) MEDIAN MNCOV . -- HTH & Regards, Dr. Marta García-Granero,PhD mailto:[hidden email] Statistician --- "It is unwise to use a statistical procedure whose use one does not understand. SPSS syntax guide cannot supply this knowledge, and it is certainly no substitute for the basic understanding of statistics and statistical thinking that is essential for the wise choice of methods and the correct interpretation of their results". (Adapted from WinPepi manual - I'm sure Joe Abrahmson will not mind) |
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