Analysis of Variance
Source     DF        SS        MS        F        p
Factor      7    815.25    116.46    75.23    0.000
Error      63     97.53      1.55
Total      70    912.77
                                   Individual 95% CIs For Mean
                                   Based on Pooled StDev
 Level      N      Mean     StDev  -------+---------+---------+---------
arctica     4    42.550     0.645                                (--*--)
polaris     7    41.157     1.118                              (-*-)
richardsoni 6    40.717     1.813                            (--*-)
nfld       25    40.016     1.443                            (*)
bangsi     10    39.430     0.769                          (-*-)
cicognathi  9    35.689     1.313                (-*-)
olympica    5    31.820     0.719      (--*-)
muricus     5    30.620     0.540   (--*-)
                                   -------+---------+---------+---------
Pooled StDev =    1.244                32.0      36.0      40.0

ANOVA of latitudinal variation in skull size of weasels (Mustela erminea)

An Analysis of variance (ANOVA) can be used to examine differences in the mean size of the skull in different weasel subspecies. The ANOVA simplifies to an F-test, in which F is the ratio of the explained (factor) to the unexplained (error) mean square (MS). The result is highly significant (p << 0.01):  more northerly subspecies (including weasels from the island of Newfoundland) have significantly larger skulls than more southerly subspecies.


Text material © 2005 by Steven M. Carr