ph: pH measurements in a chemical process

In EngrExpt: Data sets from "Introductory Statistics for Engineering Experimentation"

Description

pH measurements in a chemical process

Format

A data frame with 35 observations on the following 2 variables.

batch

a factor with levels A, B and C

ph

a numeric vector

Details

For each of three batches of material numerous pH readings were taken over the course of the production process. For this material the pH should be consistent throughout production.

References

Peter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)

Examples

str(ph)
summary(ph)
dotplot(batch ~ ph, ph, pch = 21, jitter.y = TRUE)
ph$obs <- as.integer(gl(12, 1, len = 35))
xyplot(ph ~ obs|batch, ph, type = c("g","b"), layout = c(1,3),
       strip = FALSE, strip.left = TRUE, xlab = NULL)

Example output

Loading required package: lattice
'data.frame':	35 obs. of  2 variables:
 $ batch: Factor w/ 3 levels "A","B","C": 1 1 1 1 1 1 1 1 1 1 ...
 $ ph   : num  6.13 6.5 6.74 6.6 6.53 6.45 6.5 6.55 6.38 6.55 ...
 batch        ph       
 A:12   Min.   :6.130  
 B:12   1st Qu.:6.530  
 C:11   Median :6.600  
        Mean   :6.671  
        3rd Qu.:6.770  
        Max.   :7.400  

EngrExpt documentation built on May 1, 2019, 9:15 p.m.