On 06/02/2011 02:18 AM, teriri wrote:
I have generated a plot of two empirical CDFs (attachment 1). As a
result, they are stepwise when plotted.
...
But what I need instead are smooth curves, similar to ones that are
generated from a theoretical cdf (attachment 2).
To obtain a smooth curve, you would need to estimate the density, which,
from a statistical standpoint, is a vastly different problem. Once you
have a density, however, you could integrate it to obtain the cdf:
x <- rnorm(10)
fit <- density(x)
plot(fit$x[-1],diff(fit$x)*cumsum(fit$y)[-1],type="l")
## For comparison:
plot(ecdf(x),add=TRUE,do.points=FALSE,verticals=TRUE)
Please be aware, however, that density estimation is a complicated topic
with an extensive literature.
--
Patrick Breheny
Assistant Professor
Department of Biostatistics
Department of Statistics
University of Kentucky
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