CIH CIH - Certified Industrial Hygienist Sampling Strategy and Statistical Analysis Questions and Answers 2

Question 1

What does a coefficient of variation (CV) represent in the context of analytical method performance?

Accepted Answer

The relative standard deviation, expressing precision as a percentage of the mean

Answer

The recovery efficiency of the desorption solvent

Answer

The detection limit of the analytical instrument

Answer

The ratio of field blanks to total samples collected

Question 2

According to OSHA's compliance sampling strategy, what constitutes an overexposure finding for an 8-hour TWA?

Accepted Answer

The measured TWA exceeds the PEL after accounting for sampling and analytical error

Answer

Any single sample exceeding 50% of the PEL

Answer

The geometric mean of all samples exceeds the action level

Answer

Any instantaneous reading exceeding the ceiling value

Question 3

What is the purpose of a field blank in industrial hygiene air sampling?

Accepted Answer

To detect and correct for contamination introduced during sample handling and shipping

Answer

To calibrate the sampling pump flow rate

Answer

To measure background concentrations in the general plant environment

Answer

To verify the integrity of the sampling media before use

Question 4

When sampling for a substance with a ceiling limit (C), what is the correct sampling duration according to OSHA guidelines?

Accepted Answer

15-minute short-term samples taken during peak exposure periods

Answer

Full 8-hour shift TWA sampling

Answer

2-hour samples averaged over the work shift

Answer

Instantaneous detector tube readings only

Question 5

What statistical tool is used to determine whether measured 95th percentile exposure significantly exceeds an OEL using lognormal exposure data?

Accepted Answer

Land's exact method or lognormal upper confidence limit on the 95th percentile

Answer

Student's t-test on raw sample values

Answer

Chi-square goodness-of-fit test

Answer

ANOVA comparing means across worker groups

Question 6

In the context of industrial hygiene sampling, what is meant by 'combined sampling and analytical error' (CSAE)?

Accepted Answer

The combined uncertainty from both field sampling and laboratory analysis expressed as a percentage

Answer

The total variability introduced only by laboratory analysis

Answer

The difference between replicate samples collected simultaneously

Answer

The error introduced by improper pump calibration alone