Claim · model-written summary
Nonlinear Weibull or gamma fits sometimes improved on linear regression but showed no consistent improvement.
- Taxon
- speciest0
- Outcome
- improvements in fite0
- Qualifier
- no consistent pattern of improvemente0
- Comparator
- simple linear regressionse0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleTreatmentSettingDirectionValue
Verbatim
e0“several cases in which non-linear Weibull or gamma functions provided improvements in fit compared to simple linear regressions, there was no consistent pattern of improvement.”
t0“In all species”
Title
Wright, Elaine Frances cIRcle (University of British Columbia) 2009. doi:10.14288/1.0088872
Other claims from this paper (19)
- Observation The exposure treatments had unimodal concentrations fitting a Weibull distribution and diurnal profiles with mid-afternoon maxima.
- Association pea yield had a significant negative linear relationship with increasing D50 ozone exposure.
- Association potato yield had a significant negative linear relationship with increasing D50 ozone exposure.
- Association bean yield had a significant negative linear relationship with increasing D50 ozone exposure.
- Association radish yield had a significant negative linear relationship with increasing D50 ozone exposure.
- Association Final harvest total-plant, stem and leaf dry weights and leaf area decreased significantly under ozone exposure.
- Association Early-growth regressions did not reach significance even at p <0.10.
- Intervention effect Neither radish cultivar had significant ozone effects in the June experiment.
- Association Radish growth was significantly reduced in the July–August and August–September plantings.
- Association Absolute growth rates of all crops and cultivars declined significantly.
- Association Relative growth rates had variable responses, with reductions significant only at p <0.10.
- Association Several crops had increased relative growth rates early in growth.
- Observation Cherry Belle radish was more ozone-sensitive than French Breakfast.
- Association Douglas-fir second flush growth declined by the end of the second exposure season.
- Association Douglas-fir leader growth was reduced in early 1990.
- Method / resource Estimated flux gave poorer fits than D50 for radish growth measures.
- Method / resource Estimated flux improved Douglas-fir second flush growth fits over D50, with significant weight and leaf-area fits at final harvest in 1989.
- Method / resource FLUXSUMM fit better than D50 in 75 percent of comparisons, but only second flush weight at harvest 5 was significant.
- Observation The authors found limited support that flux estimates improve descriptions of growth responses over exposure indices.