From: aguitatie...@hotmail.com
Sent: Friday, April 05, 2013 11:47 PM
To: r-help@r-project.org ; R Help
Subject: Reversing data transformation
Hi everybody,
I would be very grateful if you could give me your thoughts on the following
issue.
I need to perform Box-Cox (bcPowerÂÂ) transformation on my data. To do this,
I calculated lambda using the function 'ÂÂpowerTransform'ÂÂ.
powerTransform(data)
However, I got an error message when performing this function:
Convergence failure: return code = 52
I was told by John Fox that the nature of my data was probably causing the
problem so I applied the following transformation:
powerTransform(1e7*(data - 0.99*(min(data)))) [1]
And it worked! However, now when I try to check the normality of my data,
shapiro.test(data)
I get a new warning message:
Error in shapiro.test(data) :
ifault=6. This should not happen
I think this may be solved by removing the transformation I applied previously
in [1], but Iâm not sure how to do it properly.
Could anyone give me some advice?
MY DATA:
c(0.000103113, 0.000102948, 0.000104001, 0.000103794, 0.000104628,
9.2765e-05, 9.4296e-05, 9.5025e-05, 9.4978e-05, 9.8821e-05, 9.7586e-05,
9.6285e-05, 0.00010158, 0.000100919, 0.000103535, 0.000103321,
0.000102842, 0.000102315, 0.0001033, 0.000103691, 0.000102689,
0.000103248, 0.000101216, 0.000103127, 0.000103439, 0.000102818,
0.000103482, 0.00010227, 0.000104264, 0.000104672, 0.000104586,
0.000104516, 0.000104585, 0.000103804, 0.000103702, 0.000103405,
0.000104815, 0.000101718, 0.000101792, 0.000103273, 0.000102942,
0.000102522, 0.000103149, 0.0001036995, 0.0001039735, 0.000101487666666667,
0.000102796)
Thanks a lot!!
Bea
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