Re: Beta and Groups


Hi Guys

I have been pondering what Derek said about groups. I don’t think I understand the issue. The groups are defined either by the dendrogram ordering or by non-hierarchical classification. In the case of the dendrogram, the group labelling follows a simple algorithm – starting from the top of the dendrogram (the right side in PATN), the group containing the lowest sequenced object (the highest row or leftmost column in the Data Table) is ‘rotated’ to the top of the dendrogram. The process is repeated down the dendrogram. Group ‘1’ will therefore always contain the object in row 1 or the variable in column 1.

Variations in classification strategy (changing association measure or beta value, or adding ro semoving a few objects for example) should produce groups that are similar in definition, but there is less guarantee the more radical the change.

Non-hierarchical clasification will produce groups that are also generally int the order of the sequence of the rows. Object 1 is likely (but not guaranteed) to be in group ‘1’.

Once groups are defined, PATN maintains their definition. In SSH (and all other post-classification options), the group numbers displayed will be those as defined by classification.