Confusing table [Bioanalytics]
❝ […] 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) ?? 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]](img/CC80x15.png)
Dif-tor heh smusma 🖖🏼 Довге життя Україна!
![[image]](https://static.bebac.at/pics/Blue_and_yellow_ribbon_UA.png)
Helmut Schütz
![[image]](https://static.bebac.at/img/CC by.png)
The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes
Complete thread:
- Standard calibration curve Ken Peh 2014-01-13 17:20
- Standard calibration curve Ohlbe 2014-01-13 21:50
- Use of weighting factor Ken Peh 2014-01-14 16:37
- Confusing tableHelmut 2014-01-14 17:32
- Confusing table Ken Peh 2014-01-15 04:06
- Confusing tableHelmut 2014-01-14 17:32
- Use of weighting factor Ken Peh 2014-01-14 16:37
- Standard calibration curve ElMaestro 2014-01-14 10:14
- Standard calibration curve Roberto 2014-02-18 13:27
- Standard calibration curve Ohlbe 2014-02-18 14:53
- Standard calibration curve Roberto 2014-02-18 17:00
- Standard calibration curve Ohlbe 2014-02-18 14:53
- Standard calibration curve Roberto 2014-02-18 13:27
- Standard calibration curve AngusMcLean 2014-03-01 01:27
- Standard calibration curve Ohlbe 2014-01-13 21:50