Maize for Silage Hybrid Performance Comparison Disclaimer

The table below presents a summary of the possible t-test outcomes.

Interpretation of the t-test stars () for hybrid side-by-side yield comparisons.

INTERPRETATION OF PAIRED COMPARISONS

Where stars are shown below each comparison, this indicates the level of confidence that a real yield difference actually exists between the two hybrids based on the yield data. Yield superiority can only be concluded where one to three stars are present.
P VALUE CONFIDENCE LEVEL SCIENTIFIC DESIGNATION LEVEL OF SIGNIFICANCE YIELD ADVANTAGE INTERPRETATION
<0.001 >99.9% Very highly significant YES Product superiority for yield is shown. Can confidently plant a product providing no key agronomic traits are limiting, and/or if a key trait advantage exists. Check the trait ratings for any considerations.
<0.01  >99.0%   Highly significant YES  
<0.05  >95.0%   Significant YES  
<0.10  >90.0% CA Commercially Acceptable YES Not a significant result, but may be regarded as commercially acceptable from which to base a decision.
<0.10  >90.0%   Not significant NO Product superiority for yield cannot be claimed. Ignore the yield comparison and refer primarily to trait ratings to select between the products.

“The more stars () present for the comparison, the more confident we can be that the measured average side-by-side yield difference is due to an actual genetic yield difference between the two hybrids rather than just chance.”

Where a result is commercially acceptable (CA), the result is not designated as statistically significant, but it may be regarded as commercially acceptable. Where a result is not significant, we cannot conclude there is a yield difference between the hybrids. This may have two principle implications:

  1. Where the yields are very similar, and the comparison has been made over more than 20 locations, no significance may indicate there is little measurable difference between the two hybrids (i.e. they yield about the same) or;
  2. Where there appears to be a yield difference, no significance will generally indicate there are too few trial locations involved, or there have been inconsistent or fluctuating results. It is therefore, not possible to confidently indicate whether the difference is real. In this instance, growers should use the important hybrid trait ratings to select which hybrid to plant.

On the other hand, yields may appear to be very similar but still achieve significance - this happens in cases where yield variations are small and the number of trial locations is large.

A t-test analysis of statistical significance is now carried out on all Pioneer side-by-side comparisons and we take great care to base our product yield statements on the outcome.

Hybrid summaries in this publication use the following equations to calculate milk profit ($/ha), for silage harvested in 2016.

Milk Profit Advantage = Milksolids Yield Advantage/ha x Milk Payout

Where

Milksolids Yield Advantage/ha = Silage Yield Advantage (kgDM/ha) x 100 g Milksolids per kgDM fed

Milk Payout is based on an expected milksolids payout of $4.25/kg as projected by industry commentators.

* For more details on the cost of production for 2016/2017 click here