UAMS CHEM INTERN EXAM 1 UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS
Question:
1. accuracy
Answer:
agreement of results with the true value
Question:
2. precision
Answer:
reproductibility
Question:
3. mean
Answer:
the average value in a set
Question:
4. mode
Answer:
most common value in a set
Question:
5. 2SD
Answer:
95% confidence limits
Question:
6. CV
Answer:
SDx100/mean
Question:
7. standard
Answer:
substance whose exact concentrations are known
Question:
8. control
Answer:
substance having a known "range" of values
Question:
9. What is a delta check and the reason for doing one?
, Answer:
comparison of a patients results with their previous test results; help detect sample labeling errors, testing
errors, and erroneous patient results
Question:
10. What is a systematic error? Give two examples.
Answer:
errors in the system that affect all samples in the run; incorrect calibration, bad reagents, malfunctioning
dilutors or pipettes
Question:
11. What is a random error? How often can random errors occur? Give two examples.
Answer:
mistakes that occur without prediction or regularity but do not affect all samples on a run; occur as
frequently as 1:20 results; temp fluctuations, mislabeled specimen, clerical errors, carelessness
Question:
12. What is a "trend"? Give two common causes.
Answer:
gradual upward or downward movement of control values in 6 or more consecutive runs; deterioration of
reagents, standards, or instrument performance
Question:
13. What is a "shift"? Give two common causes.
Answer:
when control results fall on either side of the mean on 6 or more consecutive control runs; intro of
something new to the procedures such as a new lot of reagents or a sudden malfunction of the instrument
Question:
14. What is the purpose of the Westgard Rules?
Answer:
a combination of decision criteria, or control rules, to decide whether an analytical run is in-control or
out-of-control
Question:
15. What does each of the Westgard Rules mean and can patient results be reported?
1. 1-2S
2. 1-3S
3. 2-2S
Answer:
1. one control is >2SD; warning rule. accept the run
2. one control is >3SD; due to random or systematic error. reject the run
3. 2 or more controls are >2SD on the same day of testing or one control is >2SD on two consecutive runs.
suggests systematic error. reject the run
Question:
16. What does MSDS stand for and why is it important to have one?
QUESTIONS AND CORRECT ANSWERS
Question:
1. accuracy
Answer:
agreement of results with the true value
Question:
2. precision
Answer:
reproductibility
Question:
3. mean
Answer:
the average value in a set
Question:
4. mode
Answer:
most common value in a set
Question:
5. 2SD
Answer:
95% confidence limits
Question:
6. CV
Answer:
SDx100/mean
Question:
7. standard
Answer:
substance whose exact concentrations are known
Question:
8. control
Answer:
substance having a known "range" of values
Question:
9. What is a delta check and the reason for doing one?
, Answer:
comparison of a patients results with their previous test results; help detect sample labeling errors, testing
errors, and erroneous patient results
Question:
10. What is a systematic error? Give two examples.
Answer:
errors in the system that affect all samples in the run; incorrect calibration, bad reagents, malfunctioning
dilutors or pipettes
Question:
11. What is a random error? How often can random errors occur? Give two examples.
Answer:
mistakes that occur without prediction or regularity but do not affect all samples on a run; occur as
frequently as 1:20 results; temp fluctuations, mislabeled specimen, clerical errors, carelessness
Question:
12. What is a "trend"? Give two common causes.
Answer:
gradual upward or downward movement of control values in 6 or more consecutive runs; deterioration of
reagents, standards, or instrument performance
Question:
13. What is a "shift"? Give two common causes.
Answer:
when control results fall on either side of the mean on 6 or more consecutive control runs; intro of
something new to the procedures such as a new lot of reagents or a sudden malfunction of the instrument
Question:
14. What is the purpose of the Westgard Rules?
Answer:
a combination of decision criteria, or control rules, to decide whether an analytical run is in-control or
out-of-control
Question:
15. What does each of the Westgard Rules mean and can patient results be reported?
1. 1-2S
2. 1-3S
3. 2-2S
Answer:
1. one control is >2SD; warning rule. accept the run
2. one control is >3SD; due to random or systematic error. reject the run
3. 2 or more controls are >2SD on the same day of testing or one control is >2SD on two consecutive runs.
suggests systematic error. reject the run
Question:
16. What does MSDS stand for and why is it important to have one?
