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Optimizing standardised regenerative-dose signals according to the least-squares normalisation (LS-normalisation) procedure using an iterative scaling and fitting procedure proposed by Li et al. (2016).
lsNORM(SARdata, model = "gok", origin = FALSE,
weight = FALSE, natural.rm = TRUE,
norm.dose = NULL, maxiter = 10,
plot = TRUE)
logical(with default): logical value indicating if the growth curve should be forced to pass the origin
logical(with default): logical value indicating if the standardised natural-dose signal
should be removed from SARdata
numeric(optional): regenerative-dose used for re-scaling established gSGC.
For example, if norm.dose=100
, then the signal value for a dose value of 100 (Gy|s) will be re-scaled to unity
integer(with default): allowed maximum number of iterations during the LS-normalisation optimization process
logical(with default): logical value indicating if the results should be plotted
Return an invisible list that contains the following elements:
SAR data sets optimized using the LS-normalisation procedure
scaling factor of standardised regenerative-dose signals
number of iterations required
optimized parameters for the growth curve before LS-normalisation
minimized objective for the growth curve before LS-normalisation
average fit error for the growth curve before LS-normalisation
reduced chi-square value for the growth curve before LS-normalisation
figure of merit value for the growth curve before LS-normalisation in percent
optimized parameters for the growth curve after LS-normalisation
minimized objective for the growth curve after LS-normalisation
average fit error for the growth curve after LS-normalisation
reduced chi-square value for the growth curve after LS-normalisation
figure of merit value for the growth curve after LS-normalisation in percent
Function lsNORM is used for optimizing regenerative-dose signal data from a number of grains (aliquots) according to the least-squares normalisation (LS-normalisation) procedure outlined by Li et al. (2016) using an iterative scaling and fitting procedure. The LS-normalisation procedure for growth curve optimization involves the following steps: (1) Fit standardised regenerative-dose signals from all of the aliquots; (2) Re-scale the individual growth curve from each aliquot using a scaling factor. The scaling factor for each aliquot is determined in a way such that the sum of squared residuals is minimized. Each aliquots is treated individually, and different scaling factors are calculated for different aliquots. (3) Iterate the fitting (step 1) and re-scaling (step 2). The iterative procedure is performed repeatedly until there is negligible change in the relative standard deviation of the normalised growth curve data.
Li B, Jacobs Z, Roberts RG, 2016. Investigation of the applicability of standardised growth curves for OSL dating of quartz from Haua Fteah cave, Libya. Quaternary Geochronology, 35: 1-15.
# NOT RUN {
### Example 1:
data(SARdata)
# Use only the first five aliquots of SARdata.
Data <- SARdata[1:40,]
res_lsNORM <- lsNORM(Data, model="gok")
res_lsNORM$norm.SARdata
### Example 2 (not run):
# data(BIN)
# obj_pickBIN <- pickBINdata(BIN, Position=1:48, Grain=0,
# LType="OSL", view=FALSE)
# obj_analyseBIN <- analyseBINdata(obj_pickBIN, nfchn=3, nlchn=20)
# lsNORM(obj_analyseBIN$SARdata, norm.dose=300)
# }
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