Kruskal's MDS results
Hi Michael, Thanks for the reply. I understand that the stress is a measure of how good the algorithm managed to represent the ordinal distances between items. And I also see why it's dependent on the number of dimensions. I was hoping someone could tell me exactly what the formula for the percentual stress is. To me it's not clear how this metric is calculated. Regards, Dieter
Michael Denslow wrote:
Hi Dieter, I'll take a shot at this. As I understand it, the stress is telling you how the ordination distances compare with original dissimilarities that you calculated. It is a measure how well your ordination has done in representing the relationship of your sites. Note that the stress will differ depending on how many dimensions are used. I believe the default is k = 2 in isoMDS. Hope this helps, Michael
Dear List, I'm trying to interpret the results of the Kruskal's Non-metric Multidimensional Scaling algorithm (isoMDS, MASS package). The 'goodness of fit' is reported as "The final stress achieved (in percent)". What does this mean exactly? I've tried to google for an answer but I've not come up with a definitive answer. Regards, Dieter -- Dieter Vanderelst PhD Student Active Perception Lab University of Antwerp http://batbits.webnode.com/ Postal Address: Prinsstraat 13 B-2000 Antwerp Belgium
Michael Denslow Graduate Student I.W. Carpenter Jr. Herbarium [BOON] Department of Biology Appalachian State University Boone, North Carolina U.S.A. -- AND -- Communications Manager Southeast Regional Network of Expertise and Collections sernec.org