LabOps & Math Study Questions

The term used to describe reproducibility is:

precision

The extent to which measurements agree with the true value of the quantity being measured is known as:

accuracy

Which of the following parameters of a diagnostic test will vary with the prevalence of a given disease in a population?

accuracy

The target in the figure illustrates a set of results that show a high degree of:

precision

Test precision is verified by:

comparing results from analyzing the same specimens on multiple analyzers over time

The statistical term for the average value is the:

mean

Which of the following is the formula for standard deviation?

square root of (sum of the squared differences from the mean)/(N—1)

In quality control, +2 standard deviations from the mean includes what percentage of the sample population?

approximately 95% of the sample population

An index of precision is statistically known as the:

coefficient of variation

Which of these formulas is used to calculate the coefficient of variation?

(standard deviation/mean) x 100

The reliability of a test to be positive in the presence of the disease it was designed to detect is known as:

sensitivity

The ability of a diagnostic test to accurately measure only the analyte of interest in the presence of other substances is the:

specificity

Diagnostic specificity is defined as the percentage of individuals:

without a given disease who have a negative result by a given test

What is random error?

error that is without cause

Identify the first step a laboratory manager must take in the selection of a laboratory information system.

select a LIS team

A Levy-Jennings quality control chart is shown, which represents control values for 13 consecutive analyses for a particular serum constituent. If the 14th value is below the —2 SD limit, which of the following should be done?

analysis system should be checked for a deteriorating component

Which device assists in monitoring quality control?

Both Levey-Jennings charts and Westgard rule

Preanalytical (preexamination) variables in laboratory testing include:

specimen acceptability

Which of the following statements about analytical (examination) errors is true?

analytical errors are not obvious to providers

A preanalytical error can be introduced by:

vigorously shaking of blood tube to prevent clotting

Preanalytical errors are major contributors to total laboratory errors. Which of the following is not a common preanalytical error?

failure to flag a critical value on a laboratory report

Which of the following best describes the pre-analytical phase of laboratory testing?

Collecting, labeling, and transporting the patient specimen to the laboratory

Pre-analytical variables in laboratory testing include:

Specimen collection
Transport
Preservatives used

Which of the following is not a potential source of postanalytical (postexamination) errors?

labeling the specimen at the nurses’ station

When establishing a reference range at least how many results are needed?

100

The most important diagnosis and therapeutic management decision tool used to interpret test results is:

reference intervals

A reference interval is the interval between and including the lower and upper reference limits. Determining the reference intervals that will be reported with a test result is a required element of test method validation. Which of the following is not true when establishing reference values for a new analyte is being considered?

lower and upper limits must be established for each analyte

When the exact concentration of a solute of a solution is known and is used to evaluate the concentration of an unknown solution the known solution is:

standard

The first procedure to be followed if the blood gas instrumentis out-of-control for all parameters is:

recalibrate, then repeat control

Instrument calibration verification is the process of:

Assaying calibration materials in the same manner as patient samples to confirm that the calibration of the instrument is stable throughout the reportable range

A mean value of 100 and a standard deviation of 1.8 mg/dL are obtained from a set of glucose measurements on a control solution. The 95% confidence interval in mg/dL would be:

96.4-103.6

The following data were collected on a series of 30 tests. Determination of serum uric acid control: the mean was 5.8 mg/dL; one standard deviation is 0.15 mg/dL}. If confidence limits are set at ±2 standard deviations, Which of the following represents the allowable limits of the control?

5.50 mg/dl to 6.10 mg/dL

What rule is this chart violating?

1-2s

What rule is this QC violating?

R-4s

What rule is this QC violating?

1-3s

Which of the following is the formula for calculating the molarity of a solution?

number of moles of solute/L of solution

What is the molarity of a solution that contains 18.7 g of KCI (MW = 74.5) in 500 mL of water?

0.5 M

25 g NaOH (MW = 40) are added to 0.5 L of water. What is the molarity of this solution if an additional 0.25 L of water are added?

0.83 M

Which of the following is the formula for calculating the dilution of a solution? (V = volume, C=concentration)

VI1xCl1=V2xC2

In spectrophotometry, the device that allows for a narrow band of wavelengths is the:

monochromator

What is the first step in preparing a spectrophotometer for an assay?

adjust wavelength selector

The source of radiant energy in atomic absorption spectrophotometry is:

hollow cathode lamp

The methodology based on the amount of energy absorbed by a substance as a function of its concentration and using a specific source of the same material as the substance analyzed is:

atomic absorption spectrophotometry

Which of the following statements about fluorometry is true?

a compound fluoresces when it absorbs light at one wavelength and emits light at a second wavelength

Nephelometers measure light:

scattered at a right angle to the light path

The measurement of light scattered by particles in the sample is the principle

nephelometry

Osmometry is a technique for measuring the concentration of solute particles that contribute to the osmotic pressure of a solution. The most common method used in a clinical laboratory to measure osmolality is:

freezing point depression

chromatography is based on the principle of:

differential solubility

To be analyzed by gas liquid chromatography a compound must:

be volatile or made volatile

In electrophoretic analysis, buffers:

act as a carrier for ions

On electrophoresis, distorted zones of protein separation are usually due to:

overloading of serum sample

One means of checking a spectrophotometer wavelength calibration in the visible range is by

using a:

didymium filter

Which of the following is used to verify wavelength settings for narrow bandwidth spectrophotometers?

holmium oxide glass

In a spectrophotometer, light of a specific wavelength is isolated from the light source by the:

use of a monochromator

Which of the following wavelengths is within the ultraviolet range?

340 nm

What is the immunologic method utilized in the flow cytometer?

immunofluorescence

1n flow cytometry, labeled cells:

scatter the light and emit fluorescence

Use of “standard” (universal) precautions minimizes exposure to:

bloodborne pathogens and infectious materials.

What is the most likely mode of transmission for bloodborne pathogens in laboratory acquired infections?

parenteral inoculation of blood