- #1

CloudNine

- 15

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Hi all,

I'm having a bit hard time performing error calculations on one of the lab results I got.

The lab dealt with finding collection rate of a certain material onto a wire. While inside a vial, the wire was soaked in the material for a specific period of time. Then the wire was taken out of the vial and both the wire and the vial with the remaining contents were measured.

Note that it is given that the collection rate is governed by Poisson distribution.

The collection rate is simply given by:

where:

I have an excel sheet with a couple of such measurements, and now I would like to calculate the relative error in this experiment.

From what I know, I'm dealing with a reciprocal error calculation:

(*) Error = sqrt((1/W+R)^2*sW^2) + (-W/R^2)^2*s(W+R)^2)

My questions are:

1. Does sW and s(W+R) simply equal to sqrt(W) and sqrt(W+R), respectively?

2. Since one of the parameters is a sum of 2 values - W+R, should I calculate its error by using sum-error formula: sqrt(sW^2+sR^2) rather than treating this number as a united parameter as I wrote on point 1.? But what should I plug instead of sR? I feel like I'm stuck in a recursive loop.

Also, would it require me to modify the overall error formula I used (*) in any way?

Thanks!

I'm having a bit hard time performing error calculations on one of the lab results I got.

The lab dealt with finding collection rate of a certain material onto a wire. While inside a vial, the wire was soaked in the material for a specific period of time. Then the wire was taken out of the vial and both the wire and the vial with the remaining contents were measured.

Note that it is given that the collection rate is governed by Poisson distribution.

The collection rate is simply given by:

*CR=W/(W+R)*where:

**CR**= collection rate;**W**= measuring the material content which stuck on the wire;**R**= measuring the material left in the residue in the vialI have an excel sheet with a couple of such measurements, and now I would like to calculate the relative error in this experiment.

From what I know, I'm dealing with a reciprocal error calculation:

(*) Error = sqrt((1/W+R)^2*sW^2) + (-W/R^2)^2*s(W+R)^2)

My questions are:

1. Does sW and s(W+R) simply equal to sqrt(W) and sqrt(W+R), respectively?

2. Since one of the parameters is a sum of 2 values - W+R, should I calculate its error by using sum-error formula: sqrt(sW^2+sR^2) rather than treating this number as a united parameter as I wrote on point 1.? But what should I plug instead of sR? I feel like I'm stuck in a recursive loop.

Also, would it require me to modify the overall error formula I used (*) in any way?

Thanks!

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