Strip–plot in RCBD is most appropriate in experiments dealing with two factors which are more or less equally important while the interaction is more important. This is also applicable if the two factors can be applied easily using large plots than using small plots. A typical example is a combination of irrigation system and frequency of spraying of pesticide. In this design, one treatment is applied in horizontal position while the other treatment in vertical position. As such,
both Factor A and Factor B cover large plots while the interaction is much smaller than any of the two factors. The degree of precision is more or less equal for both Factors A and B but that of the interaction is more precise than any of the two
factors.
Randomization of Factor A is done independent of the randomization of Factor B but both will be
randomized within each block. The procedure is as follows:
1. Determine the number of treatments in Factor A.
2. For Block 1, randomize the treatments in factor A in one direction (vertical or horizontal)using a randomization scheme described in RCBD. Note that all treatments must appear together as strips in one block, that is, use of two sub–blocks is not possible.
3. Determine the number of treatments in Factor B.
4. Randomize the number of treatments in Factor B by the same randomization scheme used in Factor A but is the other direction.
When each cell is completed, the combination of A and B will be
5. Follow Steps 1 to 4 for the succeeding blocks.
Following the randomization scheme above, a possible lay–out for strip–plot in RCBD with three levels of Factor A and four levels of Factor B with four replications is shown if the total area is very long and the fertility gradient is irregular or not known
It is not advisable to use very long plots because it will result to one of the factors having very long area coverage which might result to high variability within the block. As such, square or nearly square plots are recommended.
The same set of data used in previous examples will be used to have a comparison between
Split–Plot and Strip–Plot in RCBD.