CPC Research & Development Methods 2 — Questions and Answers
Question 1: In Design of Experiments (DoE), a central composite design (CCD) is most commonly used to:
- Screen for significant factors from a large set
- Fit a second-order response surface model (Correct answer)
- Randomize block effects across experimental runs
- Replicate factorial points for error estimation only
Correct answer: Fit a second-order response surface model
Central composite designs add axial (star) points to a factorial core specifically to estimate quadratic (second-order) terms in response surface methodology.
Question 2: Which statistical test is most appropriate when comparing the means of three or more independent experimental groups in a chemistry R&D study?
- Paired t-test
- Chi-square test
- One-way ANOVA (Correct answer)
- Mann-Whitney U test
Correct answer: One-way ANOVA
One-way ANOVA tests whether the means of three or more independent groups differ significantly, controlling the Type I error rate across multiple comparisons.
Question 3: In a laboratory notebook, the primary purpose of requiring a witness signature on experimental pages is to:
- Verify that the experiment was completed on time
- Establish legal proof of inventorship and conception date (Correct answer)
- Certify that all safety procedures were followed
- Confirm that the data were statistically analyzed correctly
Correct answer: Establish legal proof of inventorship and conception date
Witness signatures establish a verifiable, dated record of invention conception, which is critical in patent disputes and intellectual property proceedings.
Question 4: A scientist observes that repeat measurements of the same sample yield results that cluster tightly together but are consistently offset from the true value. This situation is best described as:
- High accuracy, low precision
- Low accuracy, high precision (Correct answer)
- High accuracy, high precision
- Low accuracy, low precision
Correct answer: Low accuracy, high precision
Tight clustering indicates high precision (reproducibility), while a consistent offset from the true value indicates low accuracy (systematic bias).
Question 5: Plackett-Burman designs are specifically valued in early-stage R&D because they efficiently:
- Optimize a response near a known optimum
- Screen many factors with a minimal number of runs (Correct answer)
- Quantify interaction effects between factors
- Generate contour plots of response surfaces
Correct answer: Screen many factors with a minimal number of runs
Plackett-Burman designs are resolution III screening designs that allow testing of N-1 factors in N runs, making them highly efficient for initial factor screening.
Question 6: When developing a new analytical method, 'robustness' testing evaluates:
- The method's ability to detect the lowest possible concentration
- The effect of small, deliberate variations in method parameters on results (Correct answer)
- Agreement between results from two different laboratories
- The linear range over which the method produces proportional responses
Correct answer: The effect of small, deliberate variations in method parameters on results
Robustness testing deliberately introduces small changes in parameters such as pH, temperature, or flow rate to determine how sensitive the method is to such variations.
Question 7: In the context of scale-up from laboratory to pilot plant, which dimensionless number is most important for ensuring similar heat transfer characteristics?
- Reynolds number
- Prandtl number
- Nusselt number (Correct answer)
- Damköhler number
Correct answer: Nusselt number
The Nusselt number directly characterizes the ratio of convective to conductive heat transfer and is central to matching heat transfer performance during scale-up.
CPC Research & Development Methods 2
In Design of Experiments (DoE), a central composite design (CCD) is most commonly used to: