Transforming and adjusting your data
22
5.3
Dealing with zeros
Rows or columns in the working data holding zero values can be removed. On the
Working Data page select Handling zeros in the Type of Adjustment panel.
Select the adjustment to be made and click on Submit to make the change.
The possible options are as follows.
Deselect Rows: Removes row not wanted in this analysis. This does not delete the
data, it only removes it from the working dataset
Deselect Columns:Removes column not wanted in this analysis. This does not delete
the data, it only removes it from the working dataset
Delete zero columns   Every column in the data set that only contains zeros is
removed.
Delete zero rows   Every row in the data set that only contains zeros is removed.
Remove sparse columns   Every column in the data set which contains < x non
zero elements is removed. The value of x is entered by the user in the At least x non
zero value text box.
Remove sparse rows   Every row in the data set which contains < x non zero
elements is removed. The value of x is entered by the user in the At least x non zero
value text box.
Beals   Beals smoothing is used on sparse data sets where many of the samples hold
a small proportion of the total species list. As the transformation only uses the
presence/absence of species, it should not be applied to good quality quantitative
data as you will be discarding much of your information. It should only be performed
on data arranged with the samples as columns. Described and discussed by Beals
(1984) and McCune (1994) respectively, each element, eij, in the data array is
replaced by:
where i is the column (sample) number, j is the row (species) number, Ni is the
number of species in column (sample) i, Bothjk is the number of samples holding both
species j and k, Samplesk is the number of samples holding species k and maxS is the
total number of columns (samples).
5.4
Transposing data
Use this option to switch the rows and columns of the data set. Like all the other
adjustments it is applied to the working data set. Select transpose in the Type of
Adjustment radio box and click on the Create working data button.
Copyright 2004  PISCES Conservation Ltd





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