ssq | R Documentation |
Each construct and element are vectors in a multidimensional space. When reducing the representation to a lower dimensional space, a loss of information (sum-of-squares) will usually occur. The output of the function shows the proportion of sum-of-squares (SSQ) explained for the elements (constructs) and the amount explained by each principal component. This allows to assess which elements (construct) are represented how well in the current representation. Also it shows how much of the total variation is explained.
ssq(
x,
along = 2,
center = 1,
normalize = 0,
g = 0,
h = 1 - g,
col.active = NA,
col.passive = NA,
...
)
x |
|
along |
Numeric. Table of sum-of-squares (SSQ) for 1=constructs, 2=elements (default). Note that currently
these calculations only make sense for biplot representations with |
center |
Numeric. The type of centering to be performed. |
normalize |
A numeric value indicating along what direction (rows, columns) to normalize by standard
deviations. |
g |
Power of the singular value matrix assigned to the left singular vectors, i.e. the constructs. |
h |
Power of the singular value matrix assigned to the right singular vectors, i.e. the elements. |
col.active |
Columns (elements) that are no supplementary points, i.e. they are used in the SVD to find principal components. default is to use all elements. |
col.passive |
Columns (elements) that are supplementary points, i.e. they are NOT used in the SVD but projected
into the component space afterwards. They do not determine the solution. Default is |
A list containing three elements:
ssq.table
: dataframe with sum-of-squares explained for element/construct by each dimension
ssq.table.cumsum
: dataframe with cumulated sum-of-squares explained for element/construct number of
dimensions
ssq.total
: total sum-of-squares after pre-transforming grid matrix
TODO: if g or h is not equal to 1 the SSQ does not measure accuracy of representation as currently the ssq of each point are set in contrast with the pre-transformed matrix.
# explained sum-of-squares for elements
ssq(bell2010)
# explained sum-of-squares for constructs
ssq(bell2010, along = 1)
# save results
s <- ssq(bell2010)
# printing options
print(s)
print(s, digits = 4)
print(s, dim = 3)
print(s, cumulated = FALSE)
# access results
names(s)
s$ssq.table
s$ssq.table.cumsum
s$ssq.total
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