Bioequivalence and Bioavailability Forum • Transparent ruler

Transparent ruler – like in the good ol’ days [Bioanalytics]

posted by ElMaestro – Denmark, 2018-11-05 23:43 (1992 d 10:26 ago) – Posting: # 19536
Views: 7,620

Hi Ohlbe and Hötzi,

Thanks for your qualified opinions.

I am inclined to do this:


lines(c(5.6, 5.6), c(4.1,18), col="green", lwd=6)

lines(c(8, 8), c(4.1,8.8 ), col="red", lwd=6)

where the red line indicates the level of noise (in this case, right of the peak) and the greeen one is the signal. Roughly.

Note that in both cases I quantify s as well as n in one direction from the baseline mean or median or whatever.

Thus I am landing at s:n = (18-4.1) / (8-4.1) = 3.6.
I am not in any way claiming this is better or worse, only that this is my idea of an approach.

If I recall correctly, if you are "a large software vendor" -and I will mention none in particular- you can also do something like:

k=3                   #a miserable sad pointless constant to make s:n look better ??

a=sd (y3[400:714])    #sd of points on the peak

b=sd (y3[800:1000])   #sd of points adjacent to the peak

sn=k*a/b

which gives a result of about 5. :-D

Personally, I would of course always adjust k so that s:n is not less than 10 or so, just to avoid questions. I mean, I care about my data because I am not a nasty person :-D

—
Pass or fail!
ElMaestro

Complete thread:

Isn't it time for an open source chromatographic format ElMaestro 2018-11-04 21:54
- Isn't it time for an open source chromatographic format nobody 2018-11-05 09:00
  - and now that we are at it ElMaestro 2018-11-05 13:53
    - and now that we are at it nobody 2018-11-05 16:33
      - and now that we are at it ElMaestro 2018-11-05 18:19
    - Transparent ruler – like in the good ol’ days Helmut 2018-11-05 20:39
      - Transparent ruler – like in the good ol’ days Ohlbe 2018-11-05 22:14
        
        Transparent ruler – like in the good ol’ daysElMaestro 2018-11-05 22:43
        
        Slow down, you move too fast […] Feelin’ Groovy Helmut 2018-11-06 02:05
        
        Slow down, you move too fast […] Feelin’ Groovy nobody 2018-11-06 09:29
        
        Yes it went a little fast ElMaestro 2018-11-06 11:09
        
        Yes it went a little fast nobody 2018-11-06 12:05
        
        Yes it went a little fast ElMaestro 2018-11-06 12:10
        
        Yes it went a little fast Helmut 2018-11-07 16:09
        
        Yes it went a little fast ElMaestro 2018-11-07 16:22
        
        Yes it went a little fast nobody 2018-11-07 18:30
        Purpose of S:N? Helmut 2018-11-08 09:46
        
        Purpose of S:N? ElMaestro 2018-11-08 22:27
        
        Purpose of S:N? nobody 2018-11-09 10:06
        
        Purpose of S:N? Helmut 2018-11-09 11:34
        
        Purpose of S:N? nobody 2018-11-09 12:08
        
        Purpose of S:N? Helmut 2018-11-09 12:34
        
        Purpose of S:N? Helmut 2018-11-09 11:26
        
        Purpose of S:N? ElMaestro 2018-11-09 13:16
- Isn't it time for an open source chromatographic format paulhurleyuk 2018-11-05 16:27