Following harvest of the trials the process to produce the NVT results begins.
Throughout the process a rigorous review of the data is conducted by all NVT participants, including the NVT:
- participating breeders
- trial service providers.
We do this to ensure:
- accuracy of data entries
- data integrity
- completeness of data
- co-variates are identified, measured, and tested
- compromised results are identified.
Only after this process is complete are the NVT results released.
To produce the NVT results, two levels of analysis are conducted. The Single Site Analysis (SSA) and the Multi Environment Trial (MET) analysis.
Single Site Analyses
The results of the Single Site Analyses (SSA) are available quickly after harvest (about 14 days) to provide growers a descriptive representation of what happened in the environmental conditions at that trial. For example, how the varieties performed with an early break or dry spring.
The SSA is conducted on a single trial at a single location in a single season. This analysis is conducted on a limited dataset, usually three plots for each variety.
The SSA is less accurate and less reliable than the Multi Environment Trial at predicting long term variety performance for a location and should only be considered in context of the season experienced.
The weakness of the SSA is that it has a low reliability to be able to repeat its results. For example, if the environmental conditions changed so would the variety rankings.
Multi Environment Trial
The Multi Environment Trial (MET) analysis produces the most accurate and reliable indicator of future variety performance.
MET analysis results are presented at an individual trial level but combine the robustness of a much larger dataset than the SSA.
The MET analysis is conducted on a five-year dataset that includes trials from a wide range of seasonal and environmental conditions. The analysis can be conducted on more than 660 plots per variety (as opposed to 3 plots/variety in the SSA) to gain an accurate and reliable result. This enables growers to select consistently high performing varieties.
The MET analysis cannot be conducted until all trials in a trial series have been harvested. The MET results are published 30 days following harvest of the final trial.