Chemometric methods application in pharmaceutical products and processes analysis and control - Computer-Aided Applications in Pharmaceutical Technology - page 84

of a three-dimensional process where for each batch I matrix X
is composed of J variables measured at K time intervals. In
order to compare batches, data sets should be arranged
according to Figure 4.5 (upper part), where variables representing
columns and different batches are sorted as rows on top of each
other. Once the scores are generated, they are further arranged to
make columns of batches become sorted as rows. Average of
scores and standard deviations defi ne limits for process monitoring
and control. In order to compare variables, each row of the matrix
consists of a whole batch, where the columns are time ordered and
contain the several variables measured at each time (Figure 4.5,
lower part).
Since each run had different duration batch alignment or
synchronization of process trajectories were performed. The goal
was to match the shape of trajectories of the variables during
granulation. The methodology used to align trajectories was dynamic
time warping. Data was also centered and scaled to unit variance, to

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Different arrangements of the data (reprinted
from Lourenço et al., 2011; with permission from
Elsevier)

Figure 4.5