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| jakeb30 said it well but just some additional thoughts. P values can be thought of as an indication of how likely the result in an experiment or trial is the result of the variable introduced. In crop trials, the variable might be something like 30 extra units of UAN or applying starter with the planter 2x2x2 instead or 2x2 to see how it will impact yield. P values of less than 0.05 are generally considered to be statistically significant.
Things that will make p values significant can be large differences in what is measured, like a 30 bu/ac increase in yield. However, a small difference may be significant when done over a large sample size. A 3 bushel improvement might not be significant when each trial is only on 5 acres, but it might be significant if each trial is 100 acres. One thing that makes crop trials so difficult to get good results from is that there is a lot of variables that can't be accounted for. Soil can vary greatly over even a small plot, and rainfall can vary as well even on a single field, and outside pressures from bugs and disease can be different in locations of a plot. Moreover, think how many times a certain hybrid that usually produces your top yield is worse than other hybrids in a particular year or field because of weather or other factors. That is why a single trial, even with a statistically significant p value, generally needs to be replicated to demonstrate the variable is really the cause of the change.
If a trial from Becks or anyone else shows a difference, it is a signal that something may be working and may be worth further research. After several replications with similar results, it may indicate that the trials are truly showing something that works. | |
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How much do you believe the Becks PFR trials?
