Median polish of two-way tables — eda

eda_pol Polishes two-way tables using median, means, or any customizable functions.

Usage

eda_pol(
  x,
  row = NULL,
  col = NULL,
  val = NULL,
  stat = median,
  plot = TRUE,
  eps = 0.01,
  maxiter = 5,
  sort = FALSE,
  p = 1,
  tukey = FALSE,
  offset = 1e-05,
  col.quant = FALSE,
  colpal = "RdYlBu",
  adj.mar = TRUE,
  res.size = 1,
  row.size = 1,
  col.size = 1,
  res.txt = TRUE,
  label.txt = TRUE
)

Arguments

x: A three column data frame
row: Name of column assigned to the row effect
col: Name of column assigned to the column effect
val: Name of column assigned to the response variable
stat: Polishing statistic (default is median)
plot: Boolean determining if an output plot should be generated
eps: Convergence tolerance parameter
maxiter: Maximum number of iterations
sort: Boolean determining if the effects row/columns should be sorted
p: Re-expression power parameter
tukey: Boolean determining if Tukey's power transformation should used. If FALSE, the Box-Cox transformation is adopted.
offset: Offset to add to values if at leat one value is 0 and the power is negative
col.quant: Boolean determining if a quantile classification scheme should be used
colpal: Color palette to adopt
adj.mar: Boolean determining if margin width needs to accomodate labels
res.size: Size of residual values in plot [0-1]
row.size: Size of row effect values in plot [0-1]
col.size: Size of column effect values in plot [0-1]
res.txt: Boolean determining if values should be added to plot
label.txt: Boolean determining if margin and column labels should be plotted

Value

A list of class eda_polish with the following named components:

long The median polish residuals with three columns: Column levels, row levels and residual values.
wide The median polish residuals table in wide form.
row Row effects table
col Column effects table
global Overall value (common value)
iter Number of iterations before polish stabilizes.
cv Table of residuals, row effects, column effects and CV values in long form.
power Transformation power applied to values prior to polishing.
IQ_row Ratio between interquartile row effect values and 80th quantile of residuals.
IQ_col Ratio between interquartile column effect values and 80th quantile of residuals.

Details

The function performs a polish on a two way table. By default, it applies a median polish, but other statistical summaries such as the mean can be passed to the function via the stat = argument. The function returns a list of row/column effects along with global and residual values. It will also generate a colored table if plot = TRUE.

References

Tukey, John W. 1977. Exploratory Data Analysis. Addison-Wesley
Median polish article

Examples

df <- data.frame(region =  rep( c("NE", "NC", "S", "W"), each = 5),
edu = rep( c("ed8", "ed9to11", "ed12", "ed13to15", "ed16"), 4),
perc = c(25.3, 25.3, 18.2, 18.3, 16.3, 32.1, 29, 18.8,
        24.3, 19, 38.8, 31, 19.3, 15.7, 16.8, 25.4, 21.1, 20.3, 24, 17.5))

M <- eda_pol(df, row = region, col = edu, val = perc, plot = FALSE)
plot(M)