Dataset with 140 patients featuring two poorly performing tests (Sens: 0.60/0.55, Spec: 0.65/0.70).
Format
A data frame with 140 rows and 4 variables:
- patient_id
Character: Patient identifier (PT001-PT140)
- GoldStandard
Factor: True status ("Negative", "Positive"), 30% positive
- PoorTest1
Factor: First poor test ("Negative", "Positive"), Sens=0.60, Spec=0.65
- PoorTest2
Factor: Second poor test ("Negative", "Positive"), Sens=0.55, Spec=0.70
- age
Numeric: Patient age in years (mean 57, SD 12)
Details
Tests with low accuracy (barely better than chance). Demonstrates handling of poorly performing diagnostic tests.
Examples
data(decisioncompare_poor)
decisioncompare(data = decisioncompare_poor, gold = "GoldStandard",
goldPositive = "Positive", test1 = "PoorTest1",
test1Positive = "Positive", test2 = "PoorTest2",
test2Positive = "Positive", test3Positive = "",
ci = TRUE)
#>
#> COMPARE MEDICAL DECISION TESTS
#>
#> character(0)
#>
#> Test 1 - Recoded Data
#> ────────────────────────────────────────────────────────────────
#> Gold Positive Gold Negative Total
#> ────────────────────────────────────────────────────────────────
#> Test Positive 33.00000 27.00000 60.00000
#> Test Negative 18.00000 62.00000 80.00000
#> Total 51.00000 89.00000 140.00000
#> ────────────────────────────────────────────────────────────────
#>
#>
#> Test 1 - Confidence Intervals
#> ────────────────────────────────────────────────────────────────────────
#> Decision Statistics Estimate Lower Upper
#> ────────────────────────────────────────────────────────────────────────
#> Apparent prevalence 42.85714 34.53395 51.48906
#> True prevalence 36.42857 28.46665 44.97790
#> Test sensitivity 64.70588 50.06820 77.56938
#> Test specificity 69.66292 59.00841 78.96506
#> Diagnostic accuracy 67.85714 59.44545 75.49469
#> Positive predictive value 55.00000 41.61191 67.87785
#> Negative predictive value 77.50000 66.79137 86.08628
#> Proportion of false positives 30.33708 21.03494 40.99159
#> Proportion of false negative 35.29412 22.43062 49.93180
#> False Discovery Rate 45.00000 32.12215 58.38809
#> False Omission Rate 22.50000 13.91372 33.20863
#> ────────────────────────────────────────────────────────────────────────
#>
#>
#> Test 2 - Recoded Data
#> ────────────────────────────────────────────────────────────────
#> Gold Positive Gold Negative Total
#> ────────────────────────────────────────────────────────────────
#> Test Positive 30.00000 32.00000 62.00000
#> Test Negative 21.00000 57.00000 78.00000
#> Total 51.00000 89.00000 140.00000
#> ────────────────────────────────────────────────────────────────
#>
#>
#> Test 2 - Confidence Intervals
#> ────────────────────────────────────────────────────────────────────────
#> Decision Statistics Estimate Lower Upper
#> ────────────────────────────────────────────────────────────────────────
#> Apparent prevalence 44.28571 35.90149 52.91687
#> True prevalence 36.42857 28.46665 44.97790
#> Test sensitivity 58.82353 44.16928 72.41570
#> Test specificity 64.04494 53.17822 73.94836
#> Diagnostic accuracy 62.14286 53.56271 70.19764
#> Positive predictive value 48.38710 35.49728 61.43609
#> Negative predictive value 73.07692 61.83560 82.49875
#> Proportion of false positives 35.95506 26.05164 46.82178
#> Proportion of false negative 41.17647 27.58430 55.83072
#> False Discovery Rate 51.61290 38.56391 64.50272
#> False Omission Rate 26.92308 17.50125 38.16440
#> ────────────────────────────────────────────────────────────────────────
#>
#>
#> Test 3 - Recoded Data
#> ────────────────────────────────────────────────────────────
#> Gold Positive Gold Negative Total
#> ────────────────────────────────────────────────────────────
#> Test Positive . . .
#> Test Negative . . .
#> Total . . .
#> ────────────────────────────────────────────────────────────
#>
#>
#> Decision Test Comparison
#> ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
#> Test Sensitivity Specificity Accuracy Positive Predictive Value Negative Predictive Value Positive Likelihood Ratio Negative Likelihood Ratio
#> ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
#> PoorTest1 64.70588 69.66292 67.85714 55.00000 77.50000 2.132898 0.5066414
#> → Limited diagnostic utility - consider combining with other tests
#> PoorTest2 58.82353 64.04494 62.14286 48.38710 73.07692 1.636029 0.6429309
#> → Limited diagnostic utility - consider combining with other tests
#> ───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
#>
#>
#> Stratified Diagnostic Accuracy
#> ───────────────────────────────────────────────────────────────────────────────────────────────────────────
#> Subgroup N Test Sensitivity Specificity Accuracy PPV NPV OPA
#> ───────────────────────────────────────────────────────────────────────────────────────────────────────────
#> ───────────────────────────────────────────────────────────────────────────────────────────────────────────
#>
#>
#> <div style="font-family: Arial, sans-serif; max-width: 800px; margin:
#> 0 auto; padding: 20px;"><h2 style="color: #2c3e50; border-bottom: 2px
#> solid #3498db;"> Clinical Summary
#>
#> Among the tests evaluated, PoorTest1 demonstrated optimal diagnostic
#> performance with 64.7% sensitivity (95% CI: [see confidence interval
#> table]), 69.7% specificity (95% CI: [see confidence interval table]),
#> 55% positive predictive value, 77.5% negative predictive value, and
#> 67.9% overall accuracy. The likelihood ratio for positive results was
#> 2.13 and for negative results was 0.51.<h3 style="color: #27ae60;
#> margin-top: 30px;"> Report Sentences
#>
#> <div style="background-color: #f8f9fa; padding: 15px; border-left: 4px
#> solid #28a745; margin: 15px 0;"><h4 style="margin-top: 0;">Methods
#> Section:
#>
#> <p style="font-style: italic; line-height: 1.6;">We compared the
#> diagnostic performance of 2 tests (PoorTest1, PoorTest2) against the
#> gold standard reference using diagnostic accuracy analysis. The study
#> included 140 cases with complete data. Performance metrics calculated
#> included sensitivity, specificity, positive and negative predictive
#> values, likelihood ratios, and overall accuracy.
#>
#> <div style="background-color: #e8f4f8; padding: 15px; border-left: 4px
#> solid #3498db; margin: 15px 0;"><h4 style="margin-top: 0;">Results
#> Section:
#>
#> <p style="font-style: italic; line-height: 1.6;">Among the tests
#> evaluated, PoorTest1 demonstrated optimal diagnostic performance with
#> 64.7% sensitivity (95% CI: [see confidence interval table]), 69.7%
#> specificity (95% CI: [see confidence interval table]), 55% positive
#> predictive value, 77.5% negative predictive value, and 67.9% overall
#> accuracy. The likelihood ratio for positive results was 2.13 and for
#> negative results was 0.51.
#>
#> <h3 style="color: #8e44ad; margin-top: 30px;"> Clinical
#> Recommendations
#>
#> <div style="background-color: #fff3cd; padding: 15px; border-radius:
#> 8px;">
#>
#> Clinical Consideration: Consider using PoorTest1 in combination with
#> other tests for optimal diagnostic accuracy.
#>
#> Implementation Note: Results should be interpreted in the context of
#> disease prevalence in your clinical population. Consider local
#> validation studies before implementation.
#>
#> <div style="font-family: Arial, sans-serif; max-width: 900px; margin:
#> 0 auto; padding: 20px;"><h2 style="color: #2c3e50; text-align: center;
#> border-bottom: 2px solid #3498db; padding-bottom: 10px;"> About
#> Medical Decision Test Comparison
#>
#> <div style="background: linear-gradient(135deg, #e3f2fd 0%, #bbdefb
#> 100%); padding: 20px; border-radius: 10px; margin: 20px 0;"><h3
#> style="color: #1565c0; margin-top: 0;"> What This Analysis Does
#>
#> <p style="line-height: 1.6; color: #333;">This tool compares the
#> diagnostic performance of multiple medical tests against a gold
#> standard reference. It systematically evaluates sensitivity,
#> specificity, predictive values, likelihood ratios, and overall
#> accuracy to help you determine which test performs best for your
#> clinical scenario.
#>
#> <div style="background-color: #f1f8e9; border: 1px solid #8bc34a;
#> padding: 20px; border-radius: 8px; margin: 20px 0;"><h3 style="color:
#> #4a7c59; margin-top: 0;"> When to Use This Analysis
#>
#> <ul style="line-height: 1.8; color: #4a7c59;">Test Validation:
#> Comparing new diagnostic methods against established standardsMethod
#> Comparison: Evaluating which of several tests performs betterClinical
#> Research: Validating biomarkers, imaging techniques, or clinical
#> assessmentsQuality Assessment: Measuring agreement between different
#> raters or methodsProtocol Development: Optimizing diagnostic
#> workflows<div style="background-color: #fff3e0; border: 1px solid
#> #ff9800; padding: 20px; border-radius: 8px; margin: 20px 0;"><h3
#> style="color: #e65100; margin-top: 0;"> How to Use This Analysis
#>
#> <ol style="line-height: 1.8; color: #e65100;">Select Gold Standard:
#> Choose your most reliable reference test (e.g., biopsy, expert
#> consensus)Choose Tests to Compare: Select 2-3 diagnostic tests you
#> want to evaluateDefine Positive Levels: Specify what constitutes a
#> "positive" result for each testConfigure Options: Enable statistical
#> comparisons, confidence intervals, or visualizations as neededRun
#> Analysis: Review results tables and clinical interpretationsCopy
#> Report: Use the auto-generated sentences for your documentation<div
#> style="background-color: #f3e5f5; border: 1px solid #9c27b0; padding:
#> 20px; border-radius: 8px; margin: 20px 0;"><h3 style="color: #6a1b9a;
#> margin-top: 0;"> Key Metrics Explained
#>
#> <div style="display: grid; grid-template-columns: 1fr 1fr; gap: 15px;
#> color: #6a1b9a;">
#>
#> Sensitivity: Probability test is positive when disease present
#> (rule-out ability)
#>
#> Specificity: Probability test is negative when disease absent (rule-in
#> ability)
#>
#> PPV: Probability of disease when test positive
#>
#> NPV: Probability of no disease when test negative
#>
#> LR+: How much positive test increases odds of disease
#>
#> LR-: How much negative test decreases odds of disease
#>
#> Accuracy: Overall probability of correct classification
#>
#> McNemar Test: Statistical comparison between paired tests
#>
#> <div style="background-color: #e8f5e8; border: 1px solid #4caf50;
#> padding: 20px; border-radius: 8px; margin: 20px 0;"><h3 style="color:
#> #2e7d32; margin-top: 0;"> Clinical Interpretation Guidelines
#>
#> <div style="display: grid; grid-template-columns: 1fr 1fr; gap: 15px;
#> color: #2e7d32;"><h4 style="margin-bottom: 5px;">Screening Tests
#> (Rule-Out):
#>
#> <p style="margin-top: 0;">• Sensitivity >=95%: Excellent
#> • NPV >=95%: High confidence
#> • Goal: Minimize false negatives
#>
#> <h4 style="margin-bottom: 5px;">Confirmatory Tests (Rule-In):
#>
#> <p style="margin-top: 0;">• Specificity >=95%: Excellent
#> • PPV >=90%: High confidence
#> • Goal: Minimize false positives
#>
#> <div style="background-color: #fff8e1; border: 1px solid #ffc107;
#> padding: 20px; border-radius: 8px; margin: 20px 0;"><h3 style="color:
#> #f57f17; margin-top: 0;"> Important Assumptions & Limitations
#>
#> <ul style="line-height: 1.6; color: #f57f17;">Gold Standard: Assumes
#> your reference test is truly accurateSample Size: Results more
#> reliable with larger, representative samplesPrevalence Dependency: PPV
#> and NPV vary with disease prevalenceMcNemar Test: Requires
#> paired/matched data for statistical comparisonsMissing Data: Cases
#> with incomplete data are excluded from analysisConfidence Intervals:
#> Calculated using Wilson method for better accuracy
#>
#> <div style='margin: 10px 0;'><div style='background-color: #eff6ff;
#> border-left: 4px solid #93c5fd; padding: 12px; margin: 8px 0;
#> border-radius: 4px;'><strong style='color: #2563eb;'> Analysis
#> Completed Successfully
#> <span style='color: #374151;'>2 diagnostic tests compared using 140
#> complete cases. Gold standard identified 51 diseased and 89 healthy
#> cases. Review comparison tables and statistical tests below.