Circuit boards data
circuit.Rd
Number of nonconformities observed in 26 successive samples of 100 printed circuit boards. Sample 6 and 20 are outside the control limits. Sample 6 was examined by a new inspector and he did not recognize several type of nonconformities that could have been present. Furthermore, the unusually large number of nonconformities in sample 20 resulted from a temperature control problem in the wave soldering machine, which was subsequently repaired. The last 20 samples are further samples collected on inspection units (each formed by 100 boards).
Usage
data(circuit)
Format
A data frame with 46 observations on the following 4 variables.
- sample
sample number
- x
number of defectives in 100 printed circuit boards (inspection unit)
- size
sample size
- trial
trial sample indicator (TRUE/FALSE)
References
Montgomery, D.C. (1991) Introduction to Statistical Quality Control, 2nd ed, New York, John Wiley & Sons, pp. 173–175
Examples
data(circuit)
describe(circuit, by = trial)
#> ── trial = FALSE ───────────────────────────────────────────────────────────────
#> Obs Mean StdDev Min Median Max
#> sample 20 36.5 5.916 27 36.5 46
#> x 20 18.3 4.714 9 18.5 28
#> size 20 100.0 0.000 100 100.0 100
#>
#> ── trial = TRUE ────────────────────────────────────────────────────────────────
#> Obs Mean StdDev Min Median Max
#> sample 26 13.50 7.649 1 13.5 26
#> x 26 19.85 7.165 5 19.0 39
#> size 26 100.00 0.000 100 100.0 100
boxplot(x/size ~ trial, data = circuit)
plot(x/size ~ sample, data = circuit, type="b")