Reference Point Proportional Calculations

For the reference point proportional relationship, a slight variation of the steps given for the zero point proportional relationship is used to calculate the dynamic signal-to-noise ratio.

The relationship between the response and signal factor for this case can be modeled as

yy¯s=β(MMs)

where y is the response, y¯s is the average from the reference standard data (data obtained with the signal factor at the reference value), M is the signal factor, Ms is the reference standard (the reference signal factor level), and β is the slope of the line fit to the signal/response data.

The reference standard response average is calculated as follows:

ys=(y1+y2++yj)r0

where y1 to yj are the response values at the reference standard signal factor level for a given control experiment.

The reference standard average is then subtracted from each response data value, for a given control experiment number, and the reference standard signal factor level is subtracted from all signal factor levels. The steps for calculating the dynamic signal-to-noise ratio for the reference proportional relationship, using the reference standard adjusted data and signal factor levels, are then given as follows:

r0 = number of noise experiments

k = number of signal factor levels

  1. Calculate the slope, β:
    β=1r((M1Ms)y1+(M2s)y2++(MkMs)yk)

    where

    r=r0((M1Ms)2+(M2Ms)2++(MkMs)2)

    and yk is the sum of the response values at signal level k.

  2. Calculate the total sum of the squares:
    ST=i=1kj=1y0(yijy¯s)2
  3. Calculate the variation caused by the linear effect:
    Sβ=1r((M1Ms)y1+(M2Ms)y2++(MkMs)yk)2
  4. Calculate the variation associated with error and nonlinearity:

    S e = S T S β
  5. Calculate the error variance:

    V e = 1 k r 0 1 S e
  6. Calculate the dynamic S/N ratio:

    n=10log1r(SβVe)Ve