True/false

1) In non-hierarchical clustering, the F test is only descriptive. Because the cases or objects are systematically assigned to clusters to maximize differences on the clustering variables, the resulting probabilities should not be interpreted as testing the null hypothesis of no differences among clusters.

2) To reduce the number of variables, a large set of variables can often be replaced by the set of cluster components.

3) Principal components are usually easier to interpret than the cluster components.

4) When cluster analysis is also used for clustering variables to identify homogeneous groups, the units used for analysis are the variables and the distance measures are computed for all pairs of variables.