Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Prediction interval for unequal replicates

  1. Feb 25, 2010 #1
    Dear experts,

    I am trying to develop an algorithm for calibration studies (analytical chemistry). The algorithm could be used for estimation of calibration parameters, limit of detection & quantitation etc. For this I have to construct a prediction interval for the calibration curve. Now the only problem which I am facing is how to deal with unequal number of replicates (i.e. unequal number of Y responses) for each X value. For the estimation of calibration curve I am using the mean of Y responses weighted by the number of replicates at each X value. If I treat each Y replicates as individual points then the prediction interval can be estimated using this formula:
    PI = YPred ± t*Se*SQRT(1+1/N+(x-xbar)2/Sxx)
    Similarly for replicates (equal number) at each X value, the formula changes to:
    PI = YPred ± t*Se*SQRT(1/m+1/N+(x-xbar)2/Sxx)
    This formula seems suitable only for equal numbder of replicates. I need your help in deciding how to use the above formula for the estimation of prediction interval for unequal number of replicates.

    Thanks in advance.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted