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

Hi Ohlbe and Hötzi,

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.
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

I could be wrong, but...

Best regards,
ElMaestro

R's base package has 274 reserved words and operators, along with 1761 functions. I can use 18 of them (about 14 of them properly). I believe this makes me the Donald Trump of programming.