This menu can be used to calculate nonparametric correlations between pairs of samples. There are
two methods available; Spearman's rank correlation and Kendall's rank correlation coefficient.
Spearman's Rank Correlation Coefficient is a measure of association between the rankings of two
variables measured on N individuals (i.e. two vectors of length N). The correlation coefficient
is calculated from the vectors of ranks for each pair of samples.
Kendall's rank correlation coefficient, tau, is a measure of association between the rankings of
two variables measured on N individuals. It is calculated as S / SQRT(NC1 * NC2). S is defined as
the sum of
SIGN(Xi - Xj) * SIGN(Yi - Yj))
over all pair of distinct units i and j. NC1 and NC2 are the number of valid
comparisons (removing ties and missing values) that can be made amongst the first
and second set of samples, respectively.
Data Arrangement
The data can be supplied either as a list of variates or as a single variate with a factor defining the groups.
| List of Variates | The samples must be supplied as a list of variates, whose names should be entered in the List of Data box |
| One Variate with Groups | The data must be supplied in one variate, specified as the Data Set. Membership of the different samples is then indicated by the Groups factor |
Test
Controls the type of nonparametric correlation test to be used.
Display
Specifies the output to be displayed.
| Test | Correlation coefficient/matrix and relevant test statistics (Spearman rank correlation only). |
| Probabilities | Probability for correlation coefficient (Kendall's tau only). |
| Correlations | Rank correlation coefficient. |
| Ranks | Ranks for each sample. |
Available Data
List variates and factors that can be used to supply the data sets and groups. The contents may change as you move from one input field
to another, so that appropriate types of data structure are listed. Double-click on a name to copy it into the current input field;
alternatively you can enter the name directly using the keyboard.
See Also