- #1
FatPhysicsBoy
- 62
- 0
I have a = {a1, a2, .., a1000}, where this set forms a distribution of photoelectrons (pe) seen by a particular photomultiplier tube (pmt) over 1000 repeated events. I then have N sets of these (N pmts), each containing 1000 pe values which I believe are indeed random and independent. So a, b, c, ... (not enough letters!) where a corresponds to pmt1, b corresponds to pmt2 etc.
a then goes into a histogram from which a mean and variance is extracted, this is then done for all N sets. I then define N variables pi = μi/μT where μi = mean from histogram i which in turn corresponds to a, and μT is the sum of the means (μi) from all N histograms.
I'm just now confused on how I'd calculate V[pi], i.e. for pmt1 given that I know E[ a ] and V[ a ]. So far I've thought that perhaps I can say μT = μ1 + μ2 + ... + μN = ((a1 + a2 + ... a1000) + (b1 + b2 + ... b1000) +... )/1000 and then therefore V[μT] = ((V[a1] + V[a2] + ... V[a1000]) + (V[b1] + V[b2] + ... V[b1000]) +... )/1000. I'm not sure however, that this is correct.. First of all I don't know if the logic is correct, and secondly I'm not sure whether the aj, bk and so on can be treated as independent and random variables (I think they are random and independent, but the means E[ a ], E[ b ] etc are not?)
Hopefully this hasn't been too confusing, and any ideas would be greatly appreciated. Cheers.
a then goes into a histogram from which a mean and variance is extracted, this is then done for all N sets. I then define N variables pi = μi/μT where μi = mean from histogram i which in turn corresponds to a, and μT is the sum of the means (μi) from all N histograms.
I'm just now confused on how I'd calculate V[pi], i.e. for pmt1 given that I know E[ a ] and V[ a ]. So far I've thought that perhaps I can say μT = μ1 + μ2 + ... + μN = ((a1 + a2 + ... a1000) + (b1 + b2 + ... b1000) +... )/1000 and then therefore V[μT] = ((V[a1] + V[a2] + ... V[a1000]) + (V[b1] + V[b2] + ... V[b1000]) +... )/1000. I'm not sure however, that this is correct.. First of all I don't know if the logic is correct, and secondly I'm not sure whether the aj, bk and so on can be treated as independent and random variables (I think they are random and independent, but the means E[ a ], E[ b ] etc are not?)
Hopefully this hasn't been too confusing, and any ideas would be greatly appreciated. Cheers.