Confusing table [Bioanalytics]

posted by Helmut Homepage – Vienna, Austria, 2014-01-14 18:32 (4151 d 08:33 ago) – Posting: # 12168
Views: 10,676

Hi Ken,

❝ […] I have gone through the paper on Weighted least square linear regression (Almeida et al., 2002)…


That’s an excellent paper, IMHO.

❝ … and example plus calculation given by Helmut.


❝ I would like to know how the values of 1/x and 1/x2 were calculated. The x is the input as given in the first column (1,2,4,8,16) :confused:?? I could not get the data as presented in the table.


x is the independent variable (in bioanalytics concentration) and y the dependent (observed) one – in BA the response (analyte/IS-ratio, peak height/area, whatsoever). The weights are not given in the table, they are simply 1/x or 1/x². Sorry for the confusion caused. The table entries are the back-calculated x-values based on the intercept/slope of the respective models given below. All calculations were done in full precision, therefore you will see some slight differences.
One example: With a response of 3.7 back-calculated values are (3.7-1.4250)/2.0185=1.13 (unweighted), (3.7-1.6109)/1.9876=1.05 (weight=1/x), and (3.7-1.7133)/1.9537=1.02 (w=1/x²). Bias is given as % relative error or 100(estimated-true)/true, e.g., 100×(1.13-1)/1=+13.0%.

❝ Kindly let me know the program in R-software that can be used to perform this calculation.


I’m not in the office right now; I will post some tomorrow.

❝ […] Also sorry to Helmut for using his example without permission.


No problem. All my posts are open-source [image].

Dif-tor heh smusma 🖖🏼 Довге життя Україна! [image]
Helmut Schütz
[image]

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes

Complete thread:

UA Flag
Activity
 Admin contact
23,424 posts in 4,927 threads, 1,674 registered users;
60 visitors (0 registered, 60 guests [including 10 identified bots]).
Forum time: 04:06 CEST (Europe/Vienna)

Every man gets a narrower and narrower field of knowledge
in which he must be an expert in order to compete with other people.
The specialist knows more and more about less and less
and finally knows everything about nothing.    Konrad Lorenz

The Bioequivalence and Bioavailability Forum is hosted by
BEBAC Ing. Helmut Schütz
HTML5