By appropriately combining features of the PLAN procedure, you can construct an extensive set of designs. The basic tools are the factor-selections, which are used in the FACTORS and TREATMENTS statements. Table 87.2 summarizes how the procedure interprets various factor-selections (assuming that the ORDERED option is not specified in the PROC PLAN statement).
Table 87.2: Factor-Selection Interpretation
Form of
Request
Interpretation
Example
Results
name=m
produce a random permutation of the integers
t=15
lists a random ordering of the numbers
name=m cyclic
cyclically permute the integers
t=5 cyclic
selects the integers 1 to 5. On the next iteration, selects 2,3,4,5,1; then 3,4,5,1,2; and so on.
name=m of n
choose a random sample of m integers (without replacement) from the set of integers
t=5 of 15
lists a random selection of 5 numbers from 1 to 15. First, the procedure selects 5 numbers and then arranges them in random order.
name=m of n ordered
has the same effect as name=m ordered
t=5 of 15 ordered
lists the integers 1 to 5 in increasing order (same as t=5 ordered)
name=m of n cyclic
permute m of the n integers
t=5 of 30 cyclic
selects the integers 1 to 5. On the next iteration, selects 2,3,4,5,6; then 3,4,5,6,7; and so on. The 30th iteration produces 30,1,2,3,4; the 31st iteration produces 1,2,3,4,5; and so on.
name=m perm
produce a list of all permutations of m integers
t=5 perm
lists the integers 1,2,3,4,5 on the first iteration; on the second lists 1,2,3,5,4; on the 119th iteration lists 5,4,3,1,2; and on the last (120th) lists 5,4,3,2,1.
name=m of n comb
choose combinations of m integers from n integers
t=3 of 5 comb
lists all combinations of 5 choose 3 integers. The first iteration is 1,2,3; the second is 1,2,4; the third is 1,2,5; and so on until the last iteration 3,4,5.
name=m of n cyclic (initial-block)
permute m of the n integers, starting with the values specified in the initial-block
t=4 of 30 cyclic (2 10 15 18)
selects the integers 2,10,15,18. On the next iteration, selects 3,11,16,19; then 4,12,17,20; and so on. The thirteenth iteration is 14,22,27,30; the fourteenth iteration is 15,23,28,1; and so on.
name=m of n cyclic (initial-block) increment
permute m of the n integers. Start with the values specified in the initial-block, then add the increment to each value.
t=4 of 30 cyclic (2 10 15 18) 2
selects the integers 2,10,15,18. On the next iteration, selects 4,12,17,20; then 6,14,19,22; and so on. The wrap occurs at the eighth iteration. The eighth iteration is 16,24,29,2; and so on.
In Table 87.2, in order for more than one iteration to appear in the plan, another name=j factor selection (with j > 1) must precede the example factor selection. For example, the following statements produce six of the iterations described in the last entry of Table 87.2.