Jökull - 01.12.1989, Side 71

1.000
1—
Eruption Sample
Similarity coeflicient
----------------1-------
Similarity coetficient
1.000 0.000
i-----------------1-----------------1----------------1-----------------1-----------------r
Eruption Sample
Fig- 7. Cluster diagram for samples, based on the
parameters C, CP, CB, CE, P, B, E, VP, VB, and VE,
(the number of plotted points in respective cells of
the Sneed- Folk diagram) as well as the calculated
Parameters elongation, sphericity, and OP-index and
their variance, and Si02. The similarity scale at the
t°p of the diagram is the Pearson correlation
coefíicient.
Mynd 7. Línurit yfir fylgni milli sýna, þegar byggt
er á sömu flokkum og á mynd 6 að viðbœttum form-
þáttunum kýlni, ílengd, OP - þœtti ogferviki þessara
þátta. Skyld sýni raðast saman í kippur vinstra meg-
ln á línuritinu. Kvarðinn efst á línuritinu er fylgni-
stuðull Pearsons.
values, all the clusters in Fig. 6 join up at a fairly
high correlation giving poor sample and cluster
separation. The strongest separation of sample clus-
ters is reached in Fig. 8.
The final cluster diagram (Fig. 9) shows a cluster-
'ng of all the variables in the present study. This
diagram illustrates which variables are highly corre-
lated and it should be useful in selecting parameters
for measurement. Variables which join up early are
highly correlated and one or two variables from
each cluster should in most cases suffice to
Fig. 8. Cluster diagram for samples, based on the
calculated parameters elongation, sphericity, and
OP-index and their variance. The similarity scale at
the top of the diagram is the Pearson correlation
coefficient.
Mynd 8. Línurit yfir fylgni milli sýna, þegar byggt
er á formþáttunum kýlni, ílengd, OP - þœtti og fer-
viki þessara þátta. Skyld sýni raðast saman í kippur
vinstra megin á línuritinu. Kvarðinn efst á línuritinu
er fylgnistuðull Pearsons.
differentiate between samples. Conversely, parame-
ters that show little correlation join up on the right
hand side of the diagram and are likely to serve as
effective sample separators.
Two major clusters join up at the extreme right of
the dendrogram. Elongation (a two dimensional
parameter) and sphericity (a three dimensional
parameter) form the beginning of a cluster which
joins up with the number of grains that plot in the
upper part of the Sneed-Folk diagram (compact,
compact-platy, compact-bladed, compact-elongate,
platy, and bladed grains). The other major cluster is
formed by two separate sub-clusters. The first one is
formed by the variance in sphericity which goes
hand in hand with the number of very platy and very
JÖKULL, No. 39, 1989 69