| welding {spaMM} | R Documentation |
Welding data set
Description
The data give the results of an unreplicated experiment for factors affecting welding quality conducted by the National Railway Corporation of Japan (Taguchi and Wu, 1980, cited in Smyth et al., 2001). It is a toy example for heteroscedastic models and is also suitable for illustrating fit of overparameterized models.
Usage
data("welding")Format
The data frame includes 16 observations on 10 variables:
- Strengh
response variable;
- ...
nine two-level factors.
Source
The data were downloaded from http://www.statsci.org/data/general/welding.txt on 2014/08/19 and are consistent with those shown in table 5 of Bergman and Hynén (1997).
References
Bergman B, Hynén A (1997) Dispersion effects from
unreplicated designs in the 2^{k-p} series.
Technometrics, 39, 191–98.
Smyth GK, Huele AF, Verbyla AP (2001). Exact and approximate REML for heteroscedastic regression. Statistical Modelling 1, 161-175.
Taguchi G, Wu Y (1980) Introduction to off-line quality control. Nagoya, Japan: Central Japan Quality Control Association.
Examples
data("welding")
## toy example from Smyth et al.
fitme(Strength ~ Drying + Material,resid.model = ~ Material+Preheating ,data=welding, method="REML")
## toy example of overparameterized model
fitme(Strength ~ Rods+Thickness*Angle+(1|Rods),resid.model = ~ Rods+Thickness*Angle ,data=welding)