BREEDER VS OVT NULL HYPOTHESIS BREEDER THERE ARE DIFFERENCES OVT THERE ARE NO DIFFERENCES ALPHA LEVEL BREEDER NONE NEEDED OVT Carmer 1976 Crop Sci 169599 20 40 CHARACTERISTICS OF TEST SITES ID: 178197
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Slide1
TESTING PHILOSOPHY
BREEDER VS. OVTSlide2
NULL HYPOTHESIS
BREEDER- THERE ARE DIFFERENCES
OVT – THERE ARE NO DIFFERENCESSlide3
ALPHA LEVEL
BREEDER – NONE NEEDED
OVT –
Carmer
1976 Crop Sci. 16:95-99.
.20 -.40Slide4
CHARACTERISTICS OF TEST SITES
BREEDER – HIGH DISCRIMINATION
OVT – REPRESENTATIVE OF GROWING REGIONSlide5
DISCRIMINATION
REGRESS ENTRY MEANS BY LOCATION ON ENTRY MEANS ACROSS LOCATIONS, Ref. Brown, Sorrels
, Coffman.
Higher ‘b’ values indicate better discriminationSlide6
REPRESENTATIVE
OVTs CONDUCTED UNDER OPTIMUM, AVERAGE, AND BELOW-AVERAGE CONDITIONS TO REPRESENT AVERAGE GROWER’S CONDITIONS… Salmon, 1951Slide7
NUMBER OF TRIALS
BREEDER HAS LIMITED SEED SO NEEDS A FEW DISCRIMINATING SITES
OVT PROGRAM NEEDS TO SAMPLE ENVIRONMENTSSlide8
HOW MANY SITES ARE USED BY OVT PROGRAMS ?Slide9
Average and median number of sites
AVERAGE
BARLEY -5
CORN – 13
COTTON – 7
SOYBEAN -10
WHEAT - 9
MEDIAN
BARLEY – 4
CORN – 9
COTTON – 6
SOYBEAN – 8
WHEAT - 7Slide10
RANGE OF ACRES PER TEST SITE
BARLEY – 10,000 TO 30,000
CORN – 31,000 TO 417,000
COTTON – 33,000 TO 294,000
SOYBEAN – 75,000 TO 680,000
WHEAT – 28,000 TO 457,000Slide11
HOW MANY TEST SITES ARE ACTUALLY NEEDED?Slide12
=
V
meanSlide13
WHAT IS AN ACCEPTABLE LEVEL OF PRECISION?
LSD = 10% OF THE MEAN SEEMS REASONABLE TO ME !Slide14
CORN EXAMPLE
AVERAGE YIELD OF 140 BU/A
LSD = 14 BU/A
NEED S.E. OF MEAN DIFFERENCE= 7.0
USING 2 YEARS
, 5
REPS THEN LOCATIONS NEEDED WOULD BE 4
AVERAGE NUMBER OF TESTS LOST = 1.5
SO I NEED 6 TESTS TO COVER 750,000 aSlide15
POINTS
NULL HYPOTHESIS – DIFF. VS. NO DIFF.
ALPHA LEVEL – NONE VS. 0.2
SITES – DISCRIMINATORY VS SAMPLE
SITE NUMBERS – FEW DISCRIM. VS DESIRED LEVEL OF PRECISION