strength: Impact Strength an Insulating Material

In mdscore: Improved Score Tests for Generalized Linear Models

Description

The dataset is a subsample of the 5 x 2 factorial experiment given by Ostle and Mensing (1963).

Usage

data(strength)

Format

A data frame with 30 observations on the following 3 variables.

cut

type of specimen cut.

lot

lof of the material – I, II, III, IV and V.

y

observations of the impact strength.

Source

Ostle B, Mensing RW (1963). Statistics in Research: Basic Concepts and Techniques for Research Workers. Iowa State University.

Examples

data(strength)
fitf <- glm(y ~ cut * lot, data = strength,family = inverse.gaussian("inverse"))
summary(fitf)
X <- model.matrix(fitf, data = strength)
fit0 <- glm(y ~ cut + lot, data = strength, family = inverse.gaussian("inverse"))
test <- mdscore(fit0, X1=X[, 7:10])
summary(test)

Example output

Loading required package: MASS

Call:
glm(formula = y ~ cut * lot, family = inverse.gaussian("inverse"), 
    data = strength)

Deviance Residuals: 
      Min         1Q     Median         3Q        Max  
-0.236043  -0.101266   0.006794   0.091202   0.237815  

Coefficients:
                      Estimate Std. Error t value Pr(>|t|)    
(Intercept)            1.01695    0.08446  12.041 1.28e-10 ***
cut Crosswise          0.32834    0.12873   2.551   0.0190 *  
lot II                 0.03200    0.12038   0.266   0.7931    
lot III                0.35920    0.12956   2.772   0.0118 *  
lot IV                 0.14135    0.12353   1.144   0.2660    
lot V                  0.82354    0.14158   5.817 1.08e-05 ***
cut Crosswise:lot II  -0.40642    0.17532  -2.318   0.0312 *  
cut Crosswise:lot III -0.10874    0.19343  -0.562   0.5802    
cut Crosswise:lot IV  -0.35028    0.18074  -1.938   0.0669 .  
cut Crosswise:lot V   -0.19515    0.20815  -0.938   0.3597    
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

(Dispersion parameter for inverse.gaussian family taken to be 0.02104379)

    Null deviance: 2.62972  on 29  degrees of freedom
Residual deviance: 0.42546  on 20  degrees of freedom
AIC: -45.157

Number of Fisher Scoring iterations: 2



               Df  Value  P-value
Score           4   7.69   0.1037
Modified score  4   6.42   0.1700

mdscore documentation built on May 2, 2019, 1:26 p.m.