Chemistry Test 1 2012

23 Questions | Total Attempts: 39

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Chemistry Quizzes & Trivia

Questions and Answers
  • 1. 
    During diagnostic accuracy studies in evidence-based laboratory medicine, a laboratory test being studied, for example, produces results that are compared with the "gold standard" of testing, which would be the currently used assay or assay system. The test method of interest is referred to as: 
    • A. 

      Candidate/reference method

    • B. 

      Reference standard

    • C. 

      Outcome study

    • D. 

      Practice test

  • 2. 
    Another way that "bias" can be defined is as _________________ error.
    • A. 

      Random

    • B. 

      Systematic

    • C. 

      Analytical

    • D. 

      Clinical

  • 3. 
    A new hormone analyzer is received in the lab. By assaying a control sample 50 times and assessing the mean and variance of the results, you are checking the ________________ of the instrument. 
    • A. 

      Sensitivity

    • B. 

      Accuracy

    • C. 

      Validity

    • D. 

      Precision

  • 4. 
    In setting the criteria for a delta check for a specific patient, which of the parameters listed below need to be considered: 
    • A. 

      Diagnosis

    • B. 

      Sensitivity of the test

    • C. 

      Physiological variation

    • D. 

      Specificity of the test

  • 5. 
    Prevalence affects which of the following test characteristics:
    • A. 

      Specificity

    • B. 

      Predictive value of a negative result

    • C. 

      Detection rate

    • D. 

      False positive rate

  • 6. 
    The students t-test: 
    • A. 

      Compares a sample mean to a population mean using the population delta

    • B. 

      Compares the means of two samples using sample statistics

    • C. 

      Assesses the means of samples before and following some intervention

    • D. 

      Assesses the significance of difference between more than two variables

  • 7. 
    Which one of the following preanalytical factors must be standardized when establishing a reference interval for an analyte?
    • A. 

      Location in which venipuncture is performed

    • B. 

      The method of specimen collection

    • C. 

      Reagents used in analyte analysis

    • D. 

      The specific method used for analysis

  • 8. 
    Calculate the clinical sensitivity for the following data: in a group of 80 patients diagnosed with sickle cell disease, 72 tested positively for it. The clinical sensitivity of this test is:
    • A. 

      111%

    • B. 

      100%

    • C. 

      90%

    • D. 

      75%

  • 9. 
    Which of the following statements provides the best definition of assayed control?
    • A. 

      A substance that can be accurately weighed or measured to produce a solution of an exactly known concentration

    • B. 

      A substance of lower purity whose concentration is determined by assay and comparison

    • C. 

      Substance with an assigned value that the manufacturer establishes by using a reference method or by using reference materials traceable to primary standards

    • D. 

      Substance with an assigned value used to set the value reported by the laboratory's method or instrument

  • 10. 
    Regarding LISs, a "bidirectional interface" between an LIS and a chemistry analyzer's computer means the
    • A. 

      Laboratorian must enter results directly into both the LIS and the analyzer

    • B. 

      Analyzer and the LIS can communicate ordering information and test results between them

    • C. 

      Analyzer can only communicate with the LIS, but the LIS cannot communicate with the analyzer

    • D. 

      LIS can only communicate with the analyzer, but the analyzer cannot communicate with the LIS

  • 11. 
    The results from QMP-LS on the last chemistry survey reported that for calcium your laboratory reported a value of 2.55 mmol/L where the group mean for your method was 2.50 mmol/L. The value for standard deviation interval cal (SDI) is? 
    • A. 

      .02

    • B. 

      1.02

    • C. 

      0.05

    • D. 

      0.75

  • 12. 
    An example of random error would be:
    • A. 

      Contaminated reagents

    • B. 

      Pipetting errors

    • C. 

      Inappropriate preparation of calibrators

    • D. 

      Low volume reagent blanks

  • 13. 
    Using an incorrect colored-stopper tube to obtain a blood sample is referred to as an _________ variable.
    • A. 

      Statistical

    • B. 

      Analytical

    • C. 

      Preanalytical

    • D. 

      Controlled

  • 14. 
    In regard to a gaussian distribution, + or - 2 SD's from the mean encompasses _____________ of values. 
    • A. 

      99.7%

    • B. 

      98.0%

    • C. 

      95.5%

    • D. 

      68.2%

  • 15. 
    Test results were obtained from 100 healthy volunteers. The frequency versus test results was plotted. The histogram was non-Gaussian. What statistical method is applied ti calculate the reference interval for the healthy population?
    • A. 

      Mean + or - 2 SD

    • B. 

      Plot cumulative frequency versus test value on probability paper and determine test values at 2.5% and 97.5%

    • C. 

      Establish test value by Receiver Operator Characteristic (ROC)

    • D. 

      Establish value using Likelihood Ratio calculations

    • E. 

      Plot log frequency versus test values and determine values at 2.5 and 97.5 %

  • 16. 
    Discriminator values are associated with:
    • A. 

      Tests with high sensitivity

    • B. 

      Tests with high sensitivity towards a specific disease

    • C. 

      Tests with high specificity and a low FPR towards a specific disease

    • D. 

      Tests with high sensitivity and low FPR towards a specific disease

  • 17. 
    The ROC is a statistical tool to calculate a test discriminator value that has:
    • A. 

      Highest sensitivity

    • B. 

      Highest specificity

    • C. 

      Lowest FPR

    • D. 

      Only a and c

    • E. 

      Only b and c

  • 18. 
    In which of the following computer devices is the content lost each time the computer is turned off:
    • A. 

      ROM

    • B. 

      CPU

    • C. 

      RAM

    • D. 

      Hard Drive

  • 19. 
    A patient's serum am cortisol was higher than the pm value. Which of the following could explain the cortisol variation:
    • A. 

      Day to day variation

    • B. 

      Recent food ingested

    • C. 

      Diurnal variation

    • D. 

      Delay in separating serum

    • E. 

      Specimen not stored properly

  • 20. 
    Analytical sensitivity is related to:
    • A. 

      Lowest concentration of analyte that can be detected and accurately quantitated

    • B. 

      The minimum cross reactivity with other analytes with similar structures

    • C. 

      Highest concentration of analyte that can be detected and accurately quantitated

    • D. 

      The highest cross reactivity with other analytes with similar structures

  • 21. 
    Method selectivity/specificity refers to:
    • A. 

      Accuracy of the method

    • B. 

      Reproducibility of the method

    • C. 

      Degree to which the method is free from interference by other species in the sample

    • D. 

      Lowest concentration that can be quantitated accurately

  • 22. 
    The assayed control value for creatinine is stated as 220 umol/L. The value obtained on the analyzer was 200 umol/L. What is the percent accuracy (error)?
    • A. 

      -9.1

    • B. 

      10.2

    • C. 

      -10.2

    • D. 

      20

  • 23. 
    Multiple choice type question: What is chemistry?
    • A. 

      Science that I dont understand

    • B. 

      Stupid

    • C. 

      Long and frustrating

    • D. 

      All the above

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