Strip Plot Design Analysis
Strip plot ANOVA online with three error strata. Common in irrigation by variety field layouts.
When to use it
Use when both factors are applied as strips perpendicular to one another (machinery passes east-west by sowing rows north-south, or variety strips by fertiliser strips). Each main effect uses a different error term; the interaction uses a third.
When NOT to use it
Do not use when one factor can be sub-plotted within the other; split-plot is more powerful for the sub-plot factor. Do not use when strips cannot actually be laid out cleanly in two perpendicular directions.
What you get
ANOVA partitioned into Block, A (vertical strips), Error a, B (horizontal strips), Error b, A x B, Error c. Three F tests using the correct error each time; three CV percents; three CD values; post-hoc letter displays.
How to interpret the output
Both main effects are tested with less precision than in a factorial RBD because each is confounded with one direction of field variation. The A x B interaction is tested with Error c, generally the smallest of the three errors. Use this design only when machinery or operations force the strip layout.
Common pitfalls
- Forgetting which error term goes with which test (three-tier mistake).
- Confusing strip-plot with split-plot.
- Reporting raw means without their CDs, which are different for each effect.
Try it in StatVeda
The Strip-Plot Design engine runs entirely in the browser. No signup, no install, no data sent to a server. Paste your data, hit Run, copy the output.
Open Strip-Plot DesignReferences
- Cochran, W. G. and Cox, G. M. (1957). Experimental Designs, 2nd edition. John Wiley and Sons, New York.
- Gomez, K. A. and Gomez, A. A. (1984). Statistical Procedures for Agricultural Research. John Wiley and Sons, New York.