NSG 550 Exam1,2,3 Diagnostic Reasoning
Wilkes University
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Exam 1 · Exam 2 · Exam 3
,Exam 1
1. A clinician is taught that the probability a patient has a disease before any
testing is performed is called the:
A. Posttest probability
B. Pretest probability
C. Positive predictive value
D. Likelihood ratio
Answer: B
Rationale: Pretest probability is the estimated probability of disease based on
prevalence, history, and risk factors before a diagnostic test is applied. Posttest
probability is calculated after incorporating test results. Predictive values and
likelihood ratios are statistical tools used to move from pretest to posttest
probability, not the pretest estimate itself.
2. Which statement best describes 'hypothetico-deductive reasoning' in clinical
practice?
A. Reviewing a checklist of all possible diagnoses for every symptom
B. Generating early diagnostic hypotheses from initial data and testing them
with further data collection
C. Waiting until all data are collected before considering any diagnosis
D. Relying solely on pattern recognition without further inquiry
Answer: B
Rationale: Hypothetico-deductive reasoning involves forming a small set of likely
hypotheses early in the encounter based on initial cues, then selectively gathering
data to confirm or refute them. This contrasts with exhaustive checklist
approaches or pure pattern recognition, which skips explicit hypothesis testing.
3. A test with high sensitivity is most useful for which purpose?
A. Confirming a diagnosis when positive
B. Ruling out disease when negative
C. Determining disease prevalence
D. Estimating cost-effectiveness of treatment
Answer: B
,Rationale: The mnemonic SnNout applies: a highly SeNsitive test, when Negative,
helps rule OUT disease because it has a low false-negative rate. High specificity
tests are better for ruling in disease when positive (SpPin).
4. A patient has a positive test result for a disease with low prevalence in the
population. What is the most likely effect on the positive predictive value (PPV)?
A. PPV will be high regardless of prevalence
B. PPV will be lower than in a high-prevalence population
C. PPV is unaffected by prevalence
D. PPV will equal sensitivity
Answer: B
Rationale: PPV is directly influenced by disease prevalence. In low-prevalence
populations, even a specific test yields more false positives relative to true
positives, lowering the PPV. This is why screening tests can have limited PPV in
low-risk populations.
5. Which type of cognitive bias occurs when a clinician gives excessive weight to
the first information obtained, shaping subsequent interpretation?
A. Confirmation bias
B. Anchoring bias
C. Availability bias
D. Premature closure
Answer: B
Rationale: Anchoring bias occurs when initial information disproportionately
influences subsequent judgment. Confirmation bias is seeking data that supports
an existing hypothesis while ignoring contradictory data. Availability bias reflects
overestimating probability based on recent or memorable cases. Premature
closure is accepting a diagnosis before it is fully verified.
6. A clinician diagnoses a patient with a viral illness because 'everyone has it
right now,' without adequately considering the patient's specific presentation.
This best exemplifies:
A. Anchoring bias
B. Availability bias
C. Diagnostic momentum
D. Base rate neglect
, Answer: B
Rationale: Availability bias occurs when a diagnosis that is easily recalled (e.g., a
currently circulating illness) is judged as more probable than warranted by the
actual clinical evidence. Diagnostic momentum refers to a label persisting through
subsequent encounters once assigned by a prior provider.
7. The likelihood ratio for a positive test (LR+) of 10 indicates:
A. The test is not useful clinically
B. A large shift toward the diagnosis being present if the test is positive
C. The test has poor specificity
D. Disease prevalence is 10%
Answer: B
Rationale: An LR+ greater than 10 produces a large and often conclusive increase
in the posttest probability of disease. LR values between 0.1 and 10 have
progressively smaller effects, and an LR near 1.0 indicates the test result does not
change the probability of disease meaningfully.
8. Which element of the history is most useful for generating a broad initial
differential diagnosis?
A. Review of systems only
B. Chief complaint and history of present illness
C. Family history alone
D. Social history alone
Answer: B
Rationale: The chief complaint and history of present illness (onset, location,
duration, characteristics, aggravating/alleviating factors, radiation, timing,
severity) provide the primary data used to generate the initial differential
diagnosis. Other elements refine and narrow the differential but are not typically
the starting point.
9. A clinician orders a test that has a specificity of 98%. If the test result is
positive, this is most useful for:
A. Ruling out disease
B. Ruling in disease
C. Estimating prevalence
D. Screening asymptomatic populations
Wilkes University
Questions and Answers| Latest Update| Guaranteed Pass
Exam 1 · Exam 2 · Exam 3
,Exam 1
1. A clinician is taught that the probability a patient has a disease before any
testing is performed is called the:
A. Posttest probability
B. Pretest probability
C. Positive predictive value
D. Likelihood ratio
Answer: B
Rationale: Pretest probability is the estimated probability of disease based on
prevalence, history, and risk factors before a diagnostic test is applied. Posttest
probability is calculated after incorporating test results. Predictive values and
likelihood ratios are statistical tools used to move from pretest to posttest
probability, not the pretest estimate itself.
2. Which statement best describes 'hypothetico-deductive reasoning' in clinical
practice?
A. Reviewing a checklist of all possible diagnoses for every symptom
B. Generating early diagnostic hypotheses from initial data and testing them
with further data collection
C. Waiting until all data are collected before considering any diagnosis
D. Relying solely on pattern recognition without further inquiry
Answer: B
Rationale: Hypothetico-deductive reasoning involves forming a small set of likely
hypotheses early in the encounter based on initial cues, then selectively gathering
data to confirm or refute them. This contrasts with exhaustive checklist
approaches or pure pattern recognition, which skips explicit hypothesis testing.
3. A test with high sensitivity is most useful for which purpose?
A. Confirming a diagnosis when positive
B. Ruling out disease when negative
C. Determining disease prevalence
D. Estimating cost-effectiveness of treatment
Answer: B
,Rationale: The mnemonic SnNout applies: a highly SeNsitive test, when Negative,
helps rule OUT disease because it has a low false-negative rate. High specificity
tests are better for ruling in disease when positive (SpPin).
4. A patient has a positive test result for a disease with low prevalence in the
population. What is the most likely effect on the positive predictive value (PPV)?
A. PPV will be high regardless of prevalence
B. PPV will be lower than in a high-prevalence population
C. PPV is unaffected by prevalence
D. PPV will equal sensitivity
Answer: B
Rationale: PPV is directly influenced by disease prevalence. In low-prevalence
populations, even a specific test yields more false positives relative to true
positives, lowering the PPV. This is why screening tests can have limited PPV in
low-risk populations.
5. Which type of cognitive bias occurs when a clinician gives excessive weight to
the first information obtained, shaping subsequent interpretation?
A. Confirmation bias
B. Anchoring bias
C. Availability bias
D. Premature closure
Answer: B
Rationale: Anchoring bias occurs when initial information disproportionately
influences subsequent judgment. Confirmation bias is seeking data that supports
an existing hypothesis while ignoring contradictory data. Availability bias reflects
overestimating probability based on recent or memorable cases. Premature
closure is accepting a diagnosis before it is fully verified.
6. A clinician diagnoses a patient with a viral illness because 'everyone has it
right now,' without adequately considering the patient's specific presentation.
This best exemplifies:
A. Anchoring bias
B. Availability bias
C. Diagnostic momentum
D. Base rate neglect
, Answer: B
Rationale: Availability bias occurs when a diagnosis that is easily recalled (e.g., a
currently circulating illness) is judged as more probable than warranted by the
actual clinical evidence. Diagnostic momentum refers to a label persisting through
subsequent encounters once assigned by a prior provider.
7. The likelihood ratio for a positive test (LR+) of 10 indicates:
A. The test is not useful clinically
B. A large shift toward the diagnosis being present if the test is positive
C. The test has poor specificity
D. Disease prevalence is 10%
Answer: B
Rationale: An LR+ greater than 10 produces a large and often conclusive increase
in the posttest probability of disease. LR values between 0.1 and 10 have
progressively smaller effects, and an LR near 1.0 indicates the test result does not
change the probability of disease meaningfully.
8. Which element of the history is most useful for generating a broad initial
differential diagnosis?
A. Review of systems only
B. Chief complaint and history of present illness
C. Family history alone
D. Social history alone
Answer: B
Rationale: The chief complaint and history of present illness (onset, location,
duration, characteristics, aggravating/alleviating factors, radiation, timing,
severity) provide the primary data used to generate the initial differential
diagnosis. Other elements refine and narrow the differential but are not typically
the starting point.
9. A clinician orders a test that has a specificity of 98%. If the test result is
positive, this is most useful for:
A. Ruling out disease
B. Ruling in disease
C. Estimating prevalence
D. Screening asymptomatic populations
