Philostics [Surveys]

posted by ElMaestro  – Denmark, 2009-12-27 14:28 (5652 d 23:10 ago) – Posting: # 4525
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Dear HS,

❝ Not quite. The assumptions in the parametric model of any given metric are independent from each other, :blahblah:

❝ Untransformed metrics have limits of [-∞, +∞], whilst log-transformed have limits of [0, +∞], but in both cases the probability equals 1 (in other words, for Cmin and Cmax the log-transformation lead to the same lower limit – I wouldn’t call it a constraint – namely zero).


Hmmmm, this I would express differently. Cmax etc varies from 0 and upwards whilst the transformed (log) Cmax etc is from -inf to +inf. Log transformed parameters (C, AUC) go from -inf to +inf.

I meant something else though: Let's for simplicity consider the subject with the highest Cmax in the dataset (log or not is not the important issue here). Now we do a parametric analysis of (log) Cmin and we consider the (log) Cmin residual e for the same subject and we disregard other factors for now (makes no difference but makes it less easy to grasp). We know something about e; the (log) Cmax is higher than average (log) Cmin so average (log) Cmin plus e will be lower than (log) Cmax for that subject.

❝ ❝ (I shall abstain from proposing parametric statistics as a potential alternative, notch notch wink wink!)


:lol3: You mean nonparametric statistics? Well, cough…


Yes, I meant nonparametric. Sorry about the meaning-disturbing typo.
EM.

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