EF {qualV} | R Documentation |
The efficiency factor is a dimensionless statistic which directly relates predictions to observed data.
EF(o, p)
o |
vector of observed values |
p |
vector of corresponding predicted values |
Two time series are compared. 'EF'
is an overall measure of
similarity between fitted and observed values. Any model giving a negative value
cannot be recommended, whereas values close to one indicate a
'near-perfect' fit.
EF |
efficiency factor |
Nash, J. E. and Sutcliffe, J. V. (1970) River flow forecasting through conceptual models part I - A discussion of principles. Journal of Hydrology, 10, 282-290.
Mayer, D. G. and Butler, D. G. (1993) Statistical Validation. Ecological Modelling, 68, 21-32.
# a constructed example x <- seq(0, 2*pi, 0.1) y <- 5 + sin(x) # a process o <- y + rnorm(x, sd=0.2) # observation with random error p <- y + 0.1 # simulation with systematic bias plot(x, o); lines(x, p) EF(o, p) # observed and measured data with non-matching time intervals data(phyto) obsb <- na.omit(obs[match(sim$t, obs$t), ]) simb <- sim[na.omit(match(obs$t, sim$t)), ] EF(obsb$y, simb$y)