R Programming Language Certification Quality Control & Assurance 4

Question 1

In R, the `ewma()` function in the `qcc` package requires specifying which key parameter that controls the weighting of recent vs. historical data?

Accepted Answer

lambda

Answer

The `lambda` parameter (0 < λ ≤ 1) in an EWMA chart controls how quickly older observations are discounted; smaller values give more weight to historical data.

Question 2

When assessing normality of residuals in an R-based quality study, which test is most appropriate for small samples (n < 50)?

Accepted Answer

Shapiro-Wilk test via shapiro.test()

Answer

`shapiro.test()` implements the Shapiro-Wilk test, which has the best power for detecting non-normality in small samples (n = 3 to 5000).

Question 3

In a Gauge R&R study conducted in R, 'reproducibility' specifically measures variation due to:

Accepted Answer

Different operators measuring the same parts

Answer

Reproducibility captures the variation that occurs when different operators (or conditions) measure the same parts, while repeatability captures the within-operator variation.

Question 4

Which R function from base R computes the range of each row in a matrix of subgroup observations, used in Xbar-R chart calculations?

Accepted Answer

apply(data, 1, function(x) diff(range(x)))

Answer

`apply()` with MARGIN=1 and a range-diff function computes the range for each subgroup row when building manual Xbar-R charts in base R.

Question 5

In R's `qcc` package, what happens when you set `plot=FALSE` in a `qcc()` call?

Accepted Answer

The control chart object is returned without displaying a plot

Answer

Setting `plot=FALSE` suppresses the graphical output but still returns the full `qcc` object with all computed statistics, limits, and violations.

R Programming Language Certification Practice Test

R Programming Language Certification Practice Test

R Programming Language Certification Quality Control & Assurance 4