Deck 3: Laboratory Statistics, Method Development and QC

Question 1

Which of the following statements usually determines the acceptable range when evaluating quality control results?

A) The range that includes 75% of the results
B) The range encompassed by ±2.5 standard deviations
C) The 95% confidence interval of the mean
D) The central 68% of results

Answer 1

The 95% confidence interval of the mean

Question 2

Which of the following is an example of nominal type data?

A) Numbers applied to numeric variables for example, cholesterol result of 250 mg/dL
B) Numbers applied to nonnumeric variables for example blood types could be coded as group O=1, group A= 2 etc.
C) Numbers that are discrete and ordered for example, 4 = most severe injury, 2 = a moderately severe and 1 = a minor injury
D) Arithmetic mean

Answer 2

Numbers applied to nonnumeric variables for example blood types could be coded as group O=1, group A= 2 etc.

Question 3

A 1_3s quality control rule violation is defined as:

A) One control result that exceeds ±3 s.
B) One control result that exceeds ±1.3s.
C) Three consecutive controls results that exceed ±3 s.
D) One control result that exceeds ±4 s.

Answer 3

One control result that exceeds ±3 s.

Question 4

Which statement listed below is a reason to reject an analytical run?

A) One control result exceeds above +1 standard deviation and the second control result exceeds -1 standard deviation from the mean.
B) Two consecutive control results exceed 2 standard deviations above or below the mean.
C) Four control results steadily increase in value but are less than ±1 standard deviation from the mean.
D) Three consecutive control results exceed plus or minus 1 standard deviation from the mean.

Question 5

Which of the following is an example of an inferential statistic?

A) Mean
B) Standard deviation
C) F- test
D) Correlation coefficient

Question 6

A graph that shows the difference between your laboratory result and a comparative method results along the x-axis and the percent difference along the y-axis is referred to as which of the following?

A) Levy-Jennings graph
B) Linear regression graph
C) CUSUM graph
D) Bias graph

Question 7

Which of the following practices is inappropriate when establishing quality controls ranges?

A) Exclusion of any quality control results greater than ±2 standard deviation from the mean
B) Compare your data to the manufacturer of the quality control material.
C) Gather quality control data for a long period of time if necessary.
D) Using control results from all shifts on which the assay is performed

Question 8

Which of the following statistics is used to qualify the strength of the relationship between two variables?

A) z- value
B) standard error of the difference
C) Confidence interval
D) Correlation coefficient

Question 9

An important difference between parametric statistics and nonparametric statistics is that nonparametric statistics is distribution free, whereas parametric statistics:

A) Assumes linearity.
B) Is sensitive to gender and age.
C) Presumes a Gaussian distribution.
D) Accepts all outliers.

Question 10

Recovery experiments, testing proficiency samples and estimating bias are all examples of procedures used to assess:

A) Accuracy.
B) Precision.
C) Coefficient of determination.
D) Total error.

Question 11

A type II error is defined as which of the following?

A) A serious misinterpretation of quality control rule violation
B) Erroneously accepting the null hypothesis, with the result that a real difference is not detected.
C) Erroneously rejecting the null hypothesis or proclaiming a difference to exist when one does not
D) Ignoring a large bias between two methods

Question 12

A significant limitation of least squares regression analysis is:

A) A large confidence intervals may result is false positives.
B) Outliers will not impact the results.
C) It may result in an incorrect decision of analytical reproducibility.
D) Nonlinearity of the data will affect both the slope and intercept.

Question 13

Analysis of variance (ANOVA) is an appropriate statistics to evaluate three or more sets of data among each other, but it does NOT reveal:

A) Which set of data is bias.
B) Which set of data is most accurate.
C) Which set of data is most precise.
D) Which set of data is not in agreement with the other data.

Question 14

Deming's linear regression analysis attempts to:

A) Compensate for shortcomings of Passing and Bablok regression analysis.
B) Overcome shortfalls in the least squared method.
C) Overcome shortfall due to quality control failures.
D) Overcome issues related to the interpretation of a Student-t test.

Question 15

The McNemar statistics using a two by two contingency table is useful for evaluating which of the following?

A) Correlation between two qualitative assays for example urine ?-hCG
B) The degree of association between two sets of data
C) Correlation between two quantitative assays for serum ?-hCG
D) Determining the source of error in a qualitative assay

Question 16

Linearity is useful for assessing:

A) Slope and bias of an analytical method.
B) A large correlation coefficient.
C) Intercept and p value of analytical method.
D) Slope and intercept of an analytical method.

Question 17

The term patient demographics refers to which type of information that is entered into a laboratory information system?

A) Patient-specific information, for example, name, age, and date of birth
B) Patient-specific information, for example, the total volume of urine collected in a 24-hour period for a creatinine clearance
C) Patient-specific information, for example, their mother's and father's first and last name
D) Patient-specific information, for example, where they were born and their religious preference

Question 18

A cross-reacting compound in a serum sample may result in which of the following?

A) A reliable result
B) A precise result
C) An accurate result
D) A discordant result

Question 19

Proportional error in a method is characterized by which of the following?

A) The magnitude of the error stays the same over a wide concentration range.
B) The magnitude of the error increases as the concentration of analyte increases.
C) The magnitude of the error decreases as the concentration of analyte increases.
D) The magnitude of the error is inversely proportional to concentration.

Question 20

A glucose result that is greater than the lower limit of detection of the method should be reported as which of the following?

A) Zero
B) Less than the detection limit value
C) The actual concentration value given by the analyzer or as calculated by the operator
D) Greater than the detection limit value

Question 21

The results of a precision study urea nitrogen are shown below. What is the per cent coefficient of variation for the study?
Mean = 15 mg/dL
Standard deviation = 1.5 mg/dL
Variance = 2.0 mg/dL

A) 1.5%
B) 2.0%
C) 10.0%
D) 15.0%

Question 22

A urea nitrogen result is falsely elevated and it was discovered that the previous sample on the sample carousel has abnormally high serum glucose. Which of the following can cause this error?

A) Pipetting an extra volume of diluents into the sample with the falsely elevated glucose
B) Carryover
C) A leak in the reagent-dispensing probe
D) Double pipetting of the sample with the elevated glucose result

Question 23

The term that describes a procedure in which the CLS compares two consecutive laboratory results on a patient is:

A) Discordant check.
B) Correlation check.
C) Limits check.
D) Delta check.

Question 24

A deteriorating light source in a spectrophotometer can result in which of the following types of errors?

A) Systematic
B) Systemic
C) Type I
D) Type II

Question 25

Which of the following is a procedure that is used to substantiate the continued accuracy of the test system throughout the laboratory reportable range of the tests result of the test system?

A) Quality control
B) Calibration
C) Bias testing
D) Regression analysis