PiscesLogoSmallerStill Dealing with zeros

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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.

 

datazeros

 

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:

 

Beals

 

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).