Mohamed Yehia Junior Egypt, 20170729 22:10 Posting: # 17626 Views: 596 

Dear All, I want to know whether we can use transformed data on Tmax to check for CI?. AS it was stated previously that if we will take Tmax into statistical considerations we will take untransformed tmax not transformed ones. Edit: Category changed; see also this post #1. [Helmut] 
ElMaestro Hero Denmark, 20170729 23:30 @ Mohamed Yehia Posting: # 17628 Views: 509 

Hi M.Y., » I want to know whether we can use transformed data on Tmax to check for CI?. AS it was stated previously that if we will take Tmax into statistical considerations we will take untransformed tmax not transformed ones. CI's on Tmax are not much in use anymore. Don't bother. I mainly see them popping up nowadays when applicants find themselves in desperate situations with deficiency letters and imminent rejection fears. That's when they try to generate all sorts of supportive funky BE results (which were never stipulated in any protocol or SAP) in the hope that quantity of tests outweighs the quality of a few wellchosen tests. — I could be wrong, but… Best regards, ElMaestro  since June 2017 having an affair with the bootstrap. 
Mohamed Yehia Junior Egypt, 20170729 23:38 @ ElMaestro Posting: # 17629 Views: 506 

» CI's on Tmax are not much in use anymore. Don't bother. Hi Elmaestro, Yes, I know that. However, I found a SAS report that generate a Non parametric analysis test on Ln transformed Tmax; thats why I am wondering is that accepted or not. Edit: Full quote removed. Please delete everything from the text of the original poster which is not necessary in understanding your answer; see also this post #5! [Helmut] 
Helmut Hero Vienna, Austria, 20170730 14:41 @ Mohamed Yehia Posting: # 17630 Views: 484 

Hi Mohamed, first of all, please read this post and follow the forum’s policy (you confirmed with the registration that you have read and accepted it)! I had to edit all of your posts… » […] However, I found a SAS report that generate a Non parametric analysis test on Ln transformed Tmax; t_{max} comes from an ordinal scale and therefore, follows a discrete distribution (dependent on the sampling schedule). Hence, a nonparametric analysis is correct in principle. However, transformations are only allowed for data coming from a ratio scale (continuous with a true zero point). Therefore, the report you found is crap. SAS is a fine piece of software but only as good as the user. This one probably was not qualified for his/her job. Common language will give you a hint whether an additive model (raw data) or a multiplicative model (logtransformed data) should be used. Every time you say “X is Y% of Z” or “X is Y% lower than Z” you should apply a logtransformation (e.g., C_{max}). If you say “the difference of X to Z is Y” you should use the raw data (e.g., t_{max}). — All the best, Helmut Schütz The quality of responses received is directly proportional to the quality of the question asked. ☼ Science Quotes 