Posted by
Ian Martin-2 on
Nov 09, 2011; 6:54pm
URL: http://spssx-discussion.165.s1.nabble.com/confidence-interval-for-geo-mean-tp4975675p4978768.html
Thanks David! I'll adapt that to my data.
Still, I am puzzled that other, fairly standard SPSS procedures will give arithmetic mean ± CI, but that nothing is built in for geo mean. Perhaps this could be implemented in the future by SPSS.
regards,
Ian
Ian D. Martin, Ph.D.
Tsuji Laboratory
University of Waterloo
Dept. of Environment & Resource Studies
On Nov 9, 2011, at 10:54 AM, David Marso wrote:
> GET FILE='C:\Program Files\SPSS\1991 U.S. General Social Survey.sav'.
> MEANS TABLES=age /CELLS GEOMETRIC .
> COMPUTE No_Break=1.
> COMPUTE L_age=LN(age).
> AGGREGATE OUTFILE * / BREAK No_Break / M_LAge=MEAN(L_age) /SdLAge=SD(L_Age)/
> N=N.
> COMPUTE #Half=IDF.T(.975,N-1)*SdLAge/SQRT(N).
> COMPUTE LCL=EXP(M_Lage-#Half).
> COMPUTE UCL=EXP(M_Lage+#Half).
> COMPUTE GMean=EXP(M_Lage).
> exe.
>
>
> Ian Martin-2 wrote:
>>
>> I can't find any way to get back transformed values for a confidence
>> interval for the geometric mean. Surely I don't need to log transform all
>> the data and do the stats and then back transform the results?
>>
>> regards,
>> Ian
>>
>> Ian D. Martin, Ph.D.
>>
>> Tsuji Laboratory
>> University of Waterloo
>> Dept. of Environment & Resource Studies
>>
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