Variance

For both Redundancy Analysis and Canonical Correspondence Analysis this tab presents tabulated data for the eigenvalues of each axis and the amount of variance present in the original data that is accounted for by the axis. It also gives summary information on your data set.

The total variance or what is more strictly termed inertia is the sum of the canonical and non-canonical Eigen values.

The output is explained below.

Number of sites - This is the number of columns in the Sample/Species array loaded as the biological file. It may be the number of transects, quadrats, pitfall traps etc.

Number of species - This is the number of rows in the Sample/Species array loaded as the biological file. It is the total number of taxa in the data set.

Number of environmental variables - This is the number of rows in the Environmental array loaded as the biological file. It is the total number of taxa in the data set.

Number of canonical axes - This is the number of axes that can be related to environmental variables.

Number of non-canonical axes - This is the number of axes that hold the residual variance unexplained by a linear combination of the environmental variables.

Total variance - This is the sum of the variance explained by the canonical and non-canonical eigenvalues.

Canonical Eigenvalues - These are the eigenvalues for the canonical axes.

% variance explained - This is the amount of the total variance in the data that is explained by each of the canonical axes.

Cumulative % variance - This is the sum total of the variance explained by the addition of each new canonical axis.

Multiple correlation species/environment scores - The analysis produces scores for each site based on either their environmental variables or species composition. This row gives, for each canonical axis, the correlation between these two scores for all the sites. The value presented is the multiple correlation coefficient produced by a multiple regression of the environmental variables and the site (sample) scores derived from the weighted average of the species as the dependent variable. This value should be viewed with caution see Problems with Species-Environment Correlation.

Kendal rank  correlation species/environment scores - The analysis produces scores for each site based on either their environmental variables or species composition. This row gives, for each canonical axis, the Kendal rank correlation between these two scores for all the sites.

Non-canonical Eigenvalues - These are the eigenvalues for the non-canonical axes and represent the variance that could not be explained by a linear combination of the environmental variables. These are the results of the residual analysis.

% variance explained - This is the amount of the total variance in the data that is explained by each of the non-canonical axes.

Cumulative % variance - This is the sum total of the variance explained by the addition of each new non-canonical axes.

These results can be printed or exported from the File menu and copied from the Edit menu. See Export Active Grid