FAQ's / Definitions / Terms
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The probability that what has occurred is a result of random chance. For our trials we set our level of significance at p = 0.10, which means if our trial returns a p-value of 0.10 or less then we are at least 90% certain that what has occurred is a result of the treatment applied, or that you could expect this result to occur nine times out of ten. If a treatment cost is low relative to the value of the commodity and we are certain that it does not lower our yield, then one could perhaps lower their significance level to say p = 0.20; at this level we are 80% certain that was has occurred is a result of the treatment applied, or we might expect this same result four times out of five.
Least significant difference (LSD) is the smallest difference between treatments that can be declared significantly different. In the case of an agronomic trial, if the LSD were equal to 2.5 bu/ac, then your difference between treatments would need to be 2.5 bushels or more in order to be able to declare the treatments different.
Coefficient of variance is the ratio of the standard deviation to the mean. It describes the extent of variability between plots relative to the average for the trial. A low CV suggests that we have done a good job of controlling the many potential sources of error in our trial, a high CV suggests that we have not done a very good job of controlling the background variability within our plots. In trials with high CVs, our ability to detect treatment effects is limited due to the high amount of variation. In agronomic field trials a CV below 10 is considered good.