| medpolish {eda} | R Documentation |
Median Polish of a Matrix
Description
medpolish fits an additive "two-way" (constant + rows + columns)
model to the values given in x using Tukey's
median polish procedure.
Usage
medpolish(x, eps=0.01, maxiter=10, trace.iter = TRUE)
plot(medpolish.obj)
print(medpolish.obj)
Details
Sweeping out for row and column effects continues
until the proportional reduction in the sum
of absolute residuals is less than eps
or until there have been maxiter iterations.
The sum of absolute residuals is printed at
each iteration of the fitting process, if trace.iter is TRUE.
medpolish returns an object of class medpolish (see below).
There are printing and plotting methods for this
class, which are invoked via by the generics
print and plot.
Value
An object of class medpolish with the following named components:
overall |
the fitted constant term. |
row |
the fitted row effects. |
col |
the fitted column effects. |
residuals |
the residuals. |
name |
the name of the dataset. |
References
Tukey (1977). E.D.A; see ref.\ in line.
See Also
median; aov which for a mean
instead of median decomposition.
Examples
## Deaths from sport parachuting; from ABC of EDA, p.224:
deaths <-
rbind(c(14,15,14),
c( 7, 4, 7),
c( 8, 2,10),
c(15, 9,10),
c( 0, 2, 0))
dimnames(deaths) <- list(c("1-24", "25-74", "75-199", "200++", "NA"),
paste(1973:1975))
deaths
(med.d <- medpolish(deaths))
plot(med.d)
## Check decomposition:
all(deaths == med.d$overall + outer(med.d$row,med.d$col, "+") + med.d$resid)