LenthPlot: Lenth's Plot of Effects

In daewr: Design and Analysis of Experiments with R

Description

Plot of the factor effects with significance levels based on robust estimation of contrast standard errors.

Usage

LenthPlot(obj, alpha = 0.05, plt = TRUE, limits = TRUE,
    xlab = "factors", ylab = "effects", faclab = NULL, cex.fac = par("cex.lab"),
    cex.axis=par("cex.axis"), adj = 1, ...)

Arguments

obj	object of class lm or vector with the factor effects.
alpha	numeric. Significance level used for the margin of error (ME) and simultaneous margin of error (SME). See Lenth(1989).
plt	logical. If TRUE, a spikes plot with the factor effects is displayed. Otherwise, no plot is produced.
limits	logical. If TRUE ME and SME limits are displayed and labeled.
xlab	character string. Used to label the x-axis. "factors" as default.
ylab	character string. Used to label the y-axis. "effects" as default.
faclab	list with components idx (numeric vector) and lab (character vector). The idx entries of effects vector (taken from obj) are labelled as lab. The rest of the effect names are blanked. If NULL all factors are labelled using the coefficients' name.
cex.fac	numeric. Character size used for the factor labels.
cex.axis	numeric. Character size used for the axis.
adj	numeric between 0 and 1. Determines where to place the "ME" (margin of error) and the "SME" (simultaneous margin of error) labels (character size of 0.9*cex.axis). 0 for extreme left hand side, 1 for extreme right hand side.
...	extra parameters passed to plot.

Details

If obj is of class lm, 2*coef(obj) is used as factor effect with the intercept term removed. Otherwise, obj should be a vector with the factor effects. Robust estimate of the contrasts standard error is used to calculate marginal (ME) and simultaneous margin of error (SME) for the provided significance (1 - alpha) level. See Lenth(1989). Spikes are used to display the factor effects. If faclab is NULL, factors are labelled with the effects or coefficient names. Otherwise, those faclab\$idx factors are labelled as faclab\$lab. The rest of the factors are blanked.

Value

The function is called mainly for its side effect. It returns a vector with the value of alpha used, the estimated PSE, ME and SME.

Author(s)

Ernesto Barrios. Extension provided by Kjetil Kjernsmo (2013).

References

Lenth, R. V. (1989). "Quick and Easy Analysis of Unreplicated Factorials". Technometrics Vol. 31, No. 4. pp. 469–473.

Examples

# Example Separate Normal plots of whole and split plot effects from an unreplicated split-plot 
data(plasma)
sol<-lm(y~A*B*C*D*E,data=plasma)
summary(sol)
# get whole plot effects and split plot effects
effects<-coef(sol)
LenthPlot(effects,alpha=.05)

Example output

Registered S3 method overwritten by 'DoE.base':
  method           from       
  factorize.factor conf.design

Call:
lm(formula = y ~ A * B * C * D * E, data = plasma)

Residuals:
ALL 32 residuals are 0: no residual degrees of freedom!

Coefficients:
               Estimate Std. Error t value Pr(>|t|)
(Intercept)    40.98125         NA      NA       NA
A1              5.91250         NA      NA       NA
B1              2.11250         NA      NA       NA
C1             -1.69375         NA      NA       NA
D1             -7.55000         NA      NA       NA
E1              1.56875         NA      NA       NA
A1:B1          -2.10625         NA      NA       NA
A1:C1           1.48750         NA      NA       NA
B1:C1          -0.42500         NA      NA       NA
A1:D1           8.28125         NA      NA       NA
B1:D1          -1.65625         NA      NA       NA
C1:D1           0.83750         NA      NA       NA
A1:E1          -2.95000         NA      NA       NA
B1:E1          -0.15000         NA      NA       NA
C1:E1          -0.06875         NA      NA       NA
D1:E1           0.51250         NA      NA       NA
A1:B1:C1        1.43125         NA      NA       NA
A1:B1:D1       -1.65000         NA      NA       NA
A1:C1:D1       -1.15625         NA      NA       NA
B1:C1:D1        0.61875         NA      NA       NA
A1:B1:E1        0.05625         NA      NA       NA
A1:C1:E1       -0.08750         NA      NA       NA
B1:C1:E1        0.45000         NA      NA       NA
A1:D1:E1       -0.40625         NA      NA       NA
B1:D1:E1       -0.09375         NA      NA       NA
C1:D1:E1        0.16250         NA      NA       NA
A1:B1:C1:D1     3.42500         NA      NA       NA
A1:B1:C1:E1    -0.21875         NA      NA       NA
A1:B1:D1:E1     0.13750         NA      NA       NA
A1:C1:D1:E1    -0.13125         NA      NA       NA
B1:C1:D1:E1     0.44375         NA      NA       NA
A1:B1:C1:D1:E1  0.12500         NA      NA       NA

Residual standard error: NaN on 0 degrees of freedom
Multiple R-squared:      1,	Adjusted R-squared:    NaN 
F-statistic:   NaN on 31 and 0 DF,  p-value: NA

    alpha       PSE        ME       SME 
0.0500000 0.6703125 1.4809925 2.8119058 

daewr documentation built on March 13, 2021, 3:01 a.m.