CPC Research & Development Methods 3 — Questions and Answers
Question 1: A researcher uses Box-Behnken design instead of a central composite design. A key advantage of Box-Behnken is that it:
- Requires fewer experimental runs than a two-level factorial
- Avoids experiments at extreme (corner) combinations of all factors simultaneously (Correct answer)
- Allows estimation of cubic terms in the model
- Provides better prediction accuracy at the design center
Correct answer: Avoids experiments at extreme (corner) combinations of all factors simultaneously
Box-Behnken designs place no experimental points at the extreme corners where all factors are simultaneously at their highest or lowest levels, which is valuable when such combinations are physically hazardous or impractical.
Question 2: In patent law, the concept of 'reduction to practice' in chemistry R&D refers to:
- Filing a provisional patent application describing the invention
- Actually making and testing the invention to demonstrate it works (Correct answer)
- Publishing experimental results in a peer-reviewed journal
- Presenting data at a scientific conference for public disclosure
Correct answer: Actually making and testing the invention to demonstrate it works
Reduction to practice means constructing or carrying out the invention and demonstrating that it works for its intended purpose; an alternative is constructive reduction to practice via a patent filing.
Question 3: During method validation, 'intermediate precision' (also called ruggedness) assesses variability due to:
- Random noise within a single analytical run
- Different operators, instruments, or days within the same laboratory (Correct answer)
- Differences between two or more separate laboratories
- Variations in sample preparation concentration
Correct answer: Different operators, instruments, or days within the same laboratory
Intermediate precision measures within-laboratory variability across deliberate changes such as analyst, instrument, day, or reagent lot, reflecting real-world within-lab variation.
Question 4: A chemist planning a long-term stability study for a new compound most appropriately applies ICH guideline:
- ICH Q1A (Correct answer)
- ICH Q2B
- ICH Q3D
- ICH Q6A
Correct answer: ICH Q1A
ICH Q1A(R2) provides the regulatory guidance on stability testing of new drug substances and products, including storage conditions and testing intervals.
Question 5: In R&D, the term 'design space' as defined by ICH Q8 refers to:
- The physical floor plan of the research laboratory
- The multidimensional combination of input variables and process parameters proven to assure quality (Correct answer)
- The set of analytical instruments available for characterization
- The range of product specifications acceptable to regulators
Correct answer: The multidimensional combination of input variables and process parameters proven to assure quality
ICH Q8 defines design space as the multidimensional combination and interaction of input variables and process parameters demonstrated to provide quality assurance.
Question 6: When calculating the limit of detection (LOD) using signal-to-noise methodology, the conventional signal-to-noise ratio threshold is:
- 2:1
- 3:1 (Correct answer)
- 5:1
- 10:1
Correct answer: 3:1
By convention, the LOD is defined as the analyte concentration giving a signal-to-noise ratio of 3:1, while the LOQ typically uses a 10:1 ratio.
Question 7: Which type of error is reduced by increasing the number of replicates in an experiment?
- Systematic error
- Random error (Correct answer)
- Gross error
- Calibration error
Correct answer: Random error
Averaging multiple replicates reduces random (indeterminate) error because random fluctuations tend to cancel, while systematic errors are not reduced by replication alone.
CPC Research & Development Methods 3
A researcher uses Box-Behnken design instead of a central composite design.
A key advantage of Box-Behnken is that it: