ABSTRACT
Charles Darwin (1876) carried out experiments with corn, Zea mays. He used
fifteen pairs of seedlings. The seedlings in each pair were of the same age and
grew together under identical conditions. One plant of each pair was cross-
fertilized, the other plant was self-fertilized. Later, Darwin observed the height
of the plants; the raw data are given in Table 8.1 (according to Hand et al.,
The data of this example cannot be permuted in the same way as the
data in previous chapters. The observations are paired. The belonging to a
pair must be retained; thus, the number of possible permutations is limited.
There is only one way to obtain permutations: the values within each pair
can be interchanged. If there is no difference in the height between cross-and
self-fertilized plants, each of these permutations has the same probability to
occur as the actually observed one.
