Hi Forum,

My variable, 'NetUse, is heavily positively skewed (N=491).

Therefore, I am attempting to apply the Box-Cox transformation to 'normalise' the data.

I'm a newbie so I have had trouble understanding and using the syntax recommended to estimate lambda in SPSS:

http://pareonline.net/pdf/v15n12.pdf (pages 8-9).

So, I went the easier route and used the online statistical tool to estimate Lambda instead:

http://www.wessa.net/rwasp_boxcoxnorm.wasp

After anchoring the variable at one, this provided an estimation of Lambda of -0.18.

I then tried to use this Lambda value (the exponent, -0.18) to transform my dataset in SPSS.

In SPSS I went to: Transform-->Compute variable-->

And, used the following numeric expression:

NetUse **-0.18

However, the output (NetUseNORMAL) seemed to provide inverse values from what I had. I.e., the cases with low NetUse had high NetUseNORMAL.

I'm no mathematician, but I'm assuming the negative fractional logarithm has some type of inverse relationship on the data.

Do I need to do some type of reversing or mirroring to correct the problem?

If so, how do I go about it?

Regards,

Matthew (M. Ed)