Abstract
Abstract Large coefficients of variation (>30%) are often associated with increased experimental variability. The objective of this study was to examine the relationships between mean square errors, yield means, coefficients of variation (CV), and plot size using statistical information compiled from past wheat field research projects. Three hundred and sixty two wheat field research projects were selected from over 2,000 published wheat experiments that included soil fertility, weed, tillage, and variety evaluation. Little or no relationship between mean square error (MSE) and mean yield or plot size was found. However, mean yields and CVs demonstrated a significant negative correlation. This work proposes decreased variability among experimental units as defined by the CV can be accomplished simply by increasing the mean yield, suggesting that the use of the CV may be improper when comparing variability of trials from similar experiments. Attempts to compare variation from similar experiments should be done using the MSE since unit differences would not be a problem. The CV should only be used when comparing variation from experiments using different metrics. Plot size in plant breeding variety trials (average of 3.59 m2) was much smaller than that in fertilizer/weed/tillage trials (average of 37.2 m2). The smaller plot size employed in the variety trials reduced the variability encountered in the estimation of the mean and is consistent with the resolution where detectable differences in soil test parameters exist and that should be treated independently.
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Claims 6
Claim · model-written summary
Mean square error showed little or no relationship with mean yield or plot size.
- Taxon
- wheat
Triticum aestivumt0 - Outcome
- mean square error (MSE)e0
- Direction
- Little or no relationshipe0
- Comparator
- mean yield or plot sizee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Little or no relationship between mean square error (MSE) and mean yield or plot size was found.”
t0“wheat”
Claim · model-written summary
Mean yield and coefficient of variation were significantly negatively correlated.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- CVse0
- Direction
- negative correlatione0
- Comparator
- mean yieldse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“mean yields and CVs demonstrated a significant negative correlation.”
t0“wheat”
Claim · model-written summary
Variety trial plots averaged 3.59 m2, smaller than fertilizer, weed and tillage trial plots.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- Plot sizee0
- Direction
- much smallere0
- Value
- 3.59 m2e0
- Qualifier
- average of 37.2 m2e0
- Comparator
- fertilizer/weed/tillage trialse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plot size in plant breeding variety trials (average of 3.59 m2) was much smaller than that in fertilizer/weed/tillage trials (average of 37.2 m2).”
t0“wheat”
Claim · model-written summary
Smaller plots in variety trials reduced variability of mean estimation.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- variability encountered in the estimation of the meane0
- Direction
- reducede0
- Comparator
- smaller plot sizee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The smaller plot size employed in the variety trials reduced the variability encountered in the estimation of the mean”
t0“wheat”
Claim · model-written summary
The authors recommend MSE for comparing variation among similar experiments.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- compare variation from similar experimentse0
- Qualifier
- using the MSEe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Attempts to compare variation from similar experiments should be done using the MSE”
t0“wheat”
Claim · model-written summary
The authors recommend CV only for comparing experiments using different metrics.
- Taxon
- wheatTriticum aestivumt0
- Outcome
- comparing variation from experiments using different metricse0
- Qualifier
- CVe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The CV should only be used when comparing variation from experiments using different metrics.”
t0“wheat”