Calculating yield loss parameters
Calculation of parameters in the re-parameterization of the Michaelis-Menten model that is commonly used to assess yield loss (the rectangular hyperbola model)
yieldLoss(object, interval = c("none", "as"), level = 0.95, display = TRUE)object |
object of class 'drc |
interval |
character string specifying the type of confidence intervals to be supplied. The default is "none". Use "as" for asymptotically-based confidence intervals. |
level |
numeric. The level for the confidence intervals. The default is 0.95. |
display |
logical. If TRUE results are displayed. Otherwise they are not (useful in simulations). |
The rectangular hyperbola model is a reparameterization of the Michaelis-Menten in terms of parameters A and I
Y_L = \frac{Id}{1+Id/A}
where d denotes the weed density and Y_L the resulting yield loss.
For each of the two parameters, a matrix with two or more columns, containing the estimates and the corresponding estimated standard errors and possibly lower and upper confidence limits.
This function is only for use with model fits based on Michaelis-Menten models.
Christian Ritz
Cousens, R. (1985). A simple model relating yield loss to weed density, Ann. Appl. Biol., 107, 239–252.
## Fitting Michaelis-Menten model met.mm.m1 <- drm(gain~dose, product, data = methionine, fct = MM.3(), pmodels = list(~1, ~factor(product), ~factor(product))) ## Yield loss parameters with standard errrors yieldLoss(met.mm.m1) ## Also showing confidence intervals yieldLoss(met.mm.m1, "as")
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