Empower CF for Pct Difference of Sample at multi timepoints

[gussimmons]

Greetings,
I'm trying to figure out how to create an Empower custom field that would allow me to calculate the percent difference for multiple samples at multiple timepoints.

My Samples are as follows:
Sample 1 at 0 Hours
Sample 2 at 0 Hours
Sample 3 at 0 Hours
Sample 1 at 4 hours
Sample 2 at 4 hours
Sample 3 at 4 hours
Sample 1 at 6 hours
Sample 2 at 6 hours
Sample 3 at 6 hours
Sample 1 at 8 hours
Sample 2 at 8 hours
Sample 3 at 8 hours

The percent difference would be calculated for each sample as follows:
(Amount for Sample X at Y hours / Amount for Sample X at 0 hours); where X = Sample number 1, 2 or 3 and Y = Hours

I’ve tried to use the following sample labels
Label; Sample Name
A0; Sample 1 at 0 Hours
B0; Sample 2 at 0 Hours
C0; Sample 3 at 0 Hours
A; Sample 1 at 4 hours
B; Sample 2 at 4 hours
C; Sample 3 at 4 hours
A; Sample 1 at 6 hours
B; Sample 2 at 6 hours
C; Sample 3 at 6 hours
A; Sample 1 at 8 hours
B; Sample 2 at 8 hours
C; Sample 3 at 8 hours

Is there a wildcard or formatting trick that would allow me to use the “SAME” command?

I have tried the following without luck at
SAME.%.%.Amount / SAME”0”.%.%.Amount
SAME.%.%.Amount / SAME0.%.%.Amount
SAME.%.%.Amount / SAME’0’.%.%.Amount

Any suggestions would be much appreciated.
Thank you

[EmpowersBane]

First create a Sample, Enumerated use as position custom field called Sample_Position. In position 0 (the Value column), write Sample 1, in position 1 write Sample 2 and in position 2 write Sample 3.

In your Sample Set, label the Sample 1,2 and 3 at 0 hours as A, B and C. For all of the samples 1-3 at X hours (2,4,6 etc), select the appropriate value from Sample_Position so for all the Sample 1s Sample_Position should have Sample 1 selected, same for Samples 2 and Samples 3. In this way, it doesnt matter what actual label you use in the sample set for Samples 1-3 at X hours since the custom field is looking for Sample_Position in the formula, as below.

Then create a peak, real, calculated custom field with search order Result Set Only, All peak and sample types, Dont select All or Nothing or Missing peak. Name this custom field X_percent_of_sample. Its important to start the naming with X as custom fields are processed in alphabetical order so X is after S. The formula is:

EQ(Sample_Position,0)*Amount/A.%.(Amount)+EQ(Sample_Position, 1)*Amount/B.%.(Amount)+EQ(Sample_Position,2)*Amount/C.%.(Amount)

The way the custom field works is for all entries with Sample_Position of 0 (i.e. Sample 1) Empower will calculate the current amount and divide it by the Amount from the previous sample labelled as A (i.e. Sample 1 at 0 hours). It can do this for multiple Sample 1s throughout the sample set, since the syntax of Empower dictates that it only considers the current sample for its calculation. Same for Sample 2- for all entries with Sample_Position of 1 (i.e. Sample 2) Empower will calculate the current amount and divide it by the Amount from the previous sample labelled as B (i.e. Sample 2 at 0 hours). Same for Sample 3 as well. In the case of Sample 3 it will divide current Amount by the Amount in the previous sample labeled as C.

The beauty to this is it will work as I said across endless timepoints so if you have samples 1-3 at 2,4,6,8,10....1000 hours - as long as you put Sample 1-3 in Sample_Position against those samples, it can always divide the current amount by the amount of samples 1-3 at 0 hours. I have tried this on some sample Empower data and it worked perfectly.

[gussimmons]

This is great!!! Thank you!!!! Much appreciated.