Types of analytical errors MCQs With Answer is a focused collection designed for B.Pharm students to master analytical error concepts in pharmaceutical analysis. This introduction covers key keywords such as systematic error, random error, gross error, precision, accuracy, bias, sampling error, instrumental error, method validation, quality control, limit of detection, and error propagation. Understanding these error types, their sources, detection (e.g., control charts, outlier tests), and mitigation (calibration, SOPs, standard additions) is essential for reliable assay results, regulatory compliance, and safe drug development. Clear examples, calculations, and corrective strategies are emphasized to build practical competence. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. Which error type is reproducible and affects accuracy but not precision?
- Random error
- Systematic error
- Gross error
- Sampling error
Correct Answer: Systematic error
Q2. Which error is caused by unpredictable fluctuations in measurements and affects precision?
- Systematic error
- Random error
- Method error
- Instrumental drift
Correct Answer: Random error
Q3. A pipette user repeatedly reads the meniscus wrong; this is mainly an example of:
- Sampling error
- Personal (operator) error
- Instrumental noise
- Proportional error
Correct Answer: Personal (operator) error
Q4. Which error increases with analyte concentration and is proportional to concentration?
- Constant error
- Proportional error
- Gross error
- Random error
Correct Answer: Proportional error
Q5. What is a common way to detect systematic bias in an analytical method?
- Repeatability study only
- Running blanks only
- Recovery studies and comparison with reference method
- Increasing sample size without controls
Correct Answer: Recovery studies and comparison with reference method
Q6. Which statistical test is commonly used to identify a single outlier in small datasets?
- t-test
- ANOVA
- Grubbs’ test
- Chi-square test
Correct Answer: Grubbs’ test
Q7. Instrumental drift over time is classified as which type of error?
- Random error
- Constant error
- Systematic error
- Sampling error
Correct Answer: Systematic error
Q8. Which error can be minimized by increasing the number of replicate measurements?
- Gross error
- Systematic error
- Random error
- Calibration error
Correct Answer: Random error
Q9. A contaminated standard leads to consistently high assay results; this is an example of:
- Random error
- Gross error
- Systematic error
- Sampling error
Correct Answer: Systematic error
Q10. Which practice best reduces sampling error in heterogeneous drug formulations?
- Using a smaller sample size
- Increasing homogenization and composite sampling
- Only sampling from the top layer
- Using expired reference standards
Correct Answer: Increasing homogenization and composite sampling
Q11. Which validation parameter assesses closeness of measured values to the true value?
- Precision
- Accuracy (trueness)
- Limit of detection
- Robustness
Correct Answer: Accuracy (trueness)
Q12. Which is a gross error example that should be excluded after investigation?
- Minor random fluctuation
- Calculator entry mistake leading to large deviation
- Small systematic bias from reagent impurity
- Consistent low-level instrumental noise
Correct Answer: Calculator entry mistake leading to large deviation
Q13. In error propagation, if z = x + y, the variance of z equals:
- Var(x) – Var(y)
- Var(x) + Var(y) + 2Cov(x,y)
- Var(x) * Var(y)
- Var(x) + Var(y)
Correct Answer: Var(x) + Var(y) + 2Cov(x,y)
Q14. Which procedure helps correct matrix effects in chromatographic assays?
- Ignoring the matrix and using pure solvent standards
- Standard addition or matrix-matched calibration
- Using smaller injection volumes only
- Reducing detector sensitivity
Correct Answer: Standard addition or matrix-matched calibration
Q15. What does a control chart primarily monitor in analytical labs?
- Only accuracy of standards
- Trends and shifts indicating systematic changes over time
- Random fluctuations that cannot be analyzed
- Chemical compatibility of reagents
Correct Answer: Trends and shifts indicating systematic changes over time
Q16. Limit of detection (LOD) is best described as:
- The highest analyte concentration measurable
- The smallest concentration reliably distinguished from blank
- The limit set by regulatory policy only
- The precision at 100% analyte level
Correct Answer: The smallest concentration reliably distinguished from blank
Q17. Which error source is most likely when ambient temperature fluctuates during an assay?
- Personal error
- Environmental error
- Sampling error
- Proportional error
Correct Answer: Environmental error
Q18. Recovery experiments are primarily used to assess:
- Precision under repeatability conditions
- Accuracy and matrix effects
- Instrumental limit of detection
- Robustness to pH changes only
Correct Answer: Accuracy and matrix effects
Q19. Which practice reduces human (personal) errors in volumetric measurements?
- Blindly trusting estimates
- Training, SOPs, and using calibrated pipettes
- Using uncalibrated glassware
- Avoiding calibration records to save time
Correct Answer: Training, SOPs, and using calibrated pipettes
Q20. Heteroscedasticity in calibration data indicates which problem?
- Constant variance across concentrations
- Variance changes with concentration, affecting weighting
- No need for regression analysis
- Perfect linearity with zero error
Correct Answer: Variance changes with concentration, affecting weighting
Q21. Which error is most likely if reagent degradation causes biased low results over weeks?
- Random error
- Systematic error due to reagent instability
- Gross error
- Sampling error
Correct Answer: Systematic error due to reagent instability
Q22. Repeatability assesses precision under which conditions?
- Different labs, different analysts
- Same analyst, same equipment, short time interval
- Different days and instruments
- Only theoretical calculations
Correct Answer: Same analyst, same equipment, short time interval
Q23. A blank correction is used to correct for which issue?
- Instrument calibration curve slope
- Background signal or reagent contribution
- Sampling homogeneity
- Contamination of the standard
Correct Answer: Background signal or reagent contribution
Q24. Which method helps distinguish between constant and proportional systematic errors?
- Single-point calibration only
- Calibration across a range and inspecting intercept and slope
- Using only a blank sample
- Performing only recovery at one concentration
Correct Answer: Calibration across a range and inspecting intercept and slope
Q25. Which term refers to closeness of replicate measurements to each other?
- Accuracy
- Robustness
- Precision
- Bias
Correct Answer: Precision
Q26. Which corrective action is appropriate when an instrument shows increased noise?
- Ignore it and continue
- Service, check electronics, and perform baseline stabilization
- Reduce sample concentrations arbitrarily
- Change analysts immediately
Correct Answer: Service, check electronics, and perform baseline stabilization
Q27. Robustness testing evaluates an analytical method’s:
- Sensitivity to purposeful small variations in method parameters
- Ability to detect single low-level impurities only
- Operator preference for equipment
- Cost efficiency exclusively
Correct Answer: Sensitivity to purposeful small variations in method parameters
Q28. Which concept quantifies systematic deviation (bias) numerically?
- Standard deviation
- Percent recovery or mean error
- Limit of detection
- Relative standard deviation only
Correct Answer: Percent recovery or mean error
Q29. Carryover between injections in chromatography produces which error type?
- Random error only
- Systematic positive bias for subsequent samples
- Sampling error from bulk mixing
- Proportional error that decreases with concentration
Correct Answer: Systematic positive bias for subsequent samples
Q30. Which action is best when a suspected gross error is found in reported results?
- Report results without comment
- Investigate root cause, repeat analysis, and document findings
- Delete the datapoint without record
- Assume it’s random and average it in
Correct Answer: Investigate root cause, repeat analysis, and document findings
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com