tensile: The Tensile Strength Experiment

In ACSWR: A Companion Package for the Book "A Course in Statistics with R"

Description

An engineer wants to find out if the cotton weight percentage in a synthetic fiber effects the tensile strength. Towards this, the cotton weight percentage is fixed at 5 different levels of 15, 20, 25, 30, and 35. Each level of the percentage is assigned 5 experimental units and the tensile strength is measured on each of them. The randomization is specified in the Run_Number column. The goal of the engineer is to investigate if the tensile strength is same across the cotton weight percentage.

Usage

data(tensile)

Format

A data frame with 25 observations on the following 4 variables.

Test_Sequence

the test sequence

Run_Number

the run number

CWP

cotton weight percentage

Tensile_Strength

the tensile strength

References

Montgomery, D. C. (1976-2012). Design and Analysis of Experiments, 8e. J.Wiley.

Examples

data(tensile)
tensile$CWP <- as.factor(tensile$CWP)
tensile_aov <- aov(Tensile_Strength~CWP, data=tensile)
summary(tensile_aov)
model.matrix(tensile_aov)

Example output

            Df Sum Sq Mean Sq F value   Pr(>F)    
CWP          4  475.8  118.94   14.76 9.13e-06 ***
Residuals   20  161.2    8.06                     
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
   (Intercept) CWP20 CWP25 CWP30 CWP35
1            1     1     0     0     0
2            1     0     0     1     0
3            1     1     0     0     0
4            1     0     0     0     1
5            1     0     0     1     0
6            1     0     0     0     0
7            1     0     1     0     0
8            1     1     0     0     0
9            1     0     1     0     0
10           1     0     0     1     0
11           1     1     0     0     0
12           1     0     0     0     0
13           1     0     1     0     0
14           1     1     0     0     0
15           1     0     0     0     0
16           1     0     0     0     1
17           1     0     0     0     1
18           1     0     1     0     0
19           1     0     0     0     0
20           1     0     1     0     0
21           1     0     0     0     1
22           1     0     0     1     0
23           1     0     0     0     1
24           1     0     0     1     0
25           1     0     0     0     0
attr(,"assign")
[1] 0 1 1 1 1
attr(,"contrasts")
attr(,"contrasts")$CWP
[1] "contr.treatment"

ACSWR documentation built on May 2, 2019, 6:53 a.m.