Cluster Analysis by Multidimensional Scaling using Systat 9

Input data are soil analyses from Daisy property, Montana (-80 mesh fraction, aqua-regia digestion, 0.5 gram aliquot). Appropriate data transformations (to create Normal distributions) have already been selected and applied.

 

Input data set

Step 1: Standardize the data (subtract mean and divide by standard deviation)

Step 2: Save as a tab-delimited file for Systat

Step 3: Run Systat

Step 4: Open the data file

Systat data window

Step 5: Transpose input data (convert rows to columns, and vice versa)

Step 6: Select elements to be included in transposed matrix, and specify that output file must be saved

Step 7: Specify name of output file

Lower right-hand corner of output file in Systat data window

Step 8: Calculate inter-column (sample) distances using Statistics Correlation option

Step 9: Specify method of distance measurement and that output data should be saved

Step 10: Specify name of output file

Lower right hand corner of triangular distance matrix (may take several minutes to generate)

Step 11: Load file of distances (created in previous step) and select Statistics Data Reduction Multidimensional Scaling option

Step 12: Specify optimisation method (Systat defaults are acceptable), and that output should be saved

Shepard diagram shows relationship between intersample distances in multielement (x-axis) and 2-dimensional (y-axis) space

MDS configurations are output to screen as well as to file

Plot created by Systat. It is not very suitable for cluster identification

Plot created in MS-Excel and MS-Paint from output file of MDS configurations


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