Study design
Diagnostic performance study requirements and dataset layout.
Requirements
- A qualitative or quantitative variable of the measured values or indications (positive/negative) of the diagnostic test.
- A qualitative variable indicating the true state (positive/negative) of each subject.
Dataset layout for a single test
Use a column for the true state variable (State), and a column for the test measured values (Test); each row has the values of the variables for a case (Subject).
| Subject (optional) | State | Test |
|---|---|---|
| 1 | Diseased | 121 |
| 2 | Diseased | 118 |
| 3 | Diseased | 124 |
| 4 | Diseased | 120 |
| 5 | Diseased | 116 |
| 6 | … | … |
| 7 | Healthy | 100 |
| 8 | Healthy | 115 |
| 9 | Healthy | 102 |
| 10 | Healthy | 98 |
| 11 | Healthy | 118 |
| … | … | … |
Dataset layout for paired tests
Use a column for the true state variable (State), and a column for each of the test measured values (Test 1, Test 2); each row has the values of the variables for a case (Subject).
| Subject (optional) | State | Test 1 | Test 2 |
|---|---|---|---|
| 1 | Diseased | 121 | 86 |
| 2 | Diseased | 118 | 90 |
| 3 | Diseased | 124 | 91 |
| 4 | Diseased | 120 | 99 |
| 5 | Diseased | 116 | 89 |
| 6 | … | … | … |
| 7 | Healthy | 100 | 70 |
| 8 | Healthy | 115 | 80 |
| 9 | Healthy | 102 | 79 |
| 10 | Healthy | 98 | 87 |
| 11 | Healthy | 118 | 90 |
| … | … | … |
Dataset layout for independent tests
Use a column for the true state variable (State), a column for the factor (test or group indicator), and a column for the test measured values (Test); each row has the values of the variables for a case (Subject).
| Subject (optional) | State | Test/Group ID | Test result |
|---|---|---|---|
| 1 | Diseased | 1 | 121 |
| 2 | Diseased | 1 | 118 |
| 3 | Diseased | 1 | 124 |
| 4 | Diseased | 1 | 120 |
| 5 | Diseased | 1 | 116 |
| 6 | Healthy | 1 | 100 |
| 7 | Healthy | 1 | 115 |
| 8 | Healthy | 1 | 102 |
| 9 | Healthy | 1 | 98 |
| 10 | Healthy | 1 | 118 |
| 11 | … | … | … |
| 12 | Diseased | 2 | 86 |
| 13 | Diseased | 2 | 90 |
| 14 | Diseased | 2 | 91 |
| 15 | Diseased | 2 | 99 |
| 16 | Diseased | 2 | 89 |
| 17 | Healthy | 2 | 70 |
| 18 | Healthy | 2 | 80 |
| 19 | Healthy | 2 | 79 |
| 20 | Healthy | 2 | 87 |
| 21 | Healthy | 2 | 90 |
| … | … | … | … |
Dataset layout for a single binary test
Use a column for the true state variable (State), and a column for the test indications (Test); each row has the values of the variables for a case (Subject).
| Subject (optional) | State | Test |
|---|---|---|
| 1 | Diseased | P |
| 2 | Diseased | P |
| 3 | Diseased | P |
| 4 | Diseased | N |
| 5 | Diseased | P |
| 6 | Healthy | N |
| 7 | Healthy | N |
| 8 | Healthy | N |
| 9 | Healthy | N |
| 10 | Healthy | N |
| … | … | … |
Frequency form dataset layout for a binary test
Use a column for the true state variable (State), and a column for the test indications (Test) and a column for the number of cases (Frequency); each row has the values of the variables and the frequency count.
| State | Test | Count |
|---|---|---|
| Diseased | Positive | 3 |
| Diseased | Negative | 1 |
| Healthy | Positive | 0 |
| Healthy | Negative | 5 |
Frequency form dataset layout for 2 independent binary tests
Use a column for the true state variable (State), a column for the factor (test or group indicator), a column for the test indications (Test) and a column for the number of cases (Frequency); each row has the values of the variables and the frequency count.
| State | Test | Group/Test ID | Count |
|---|---|---|---|
| Diseased | Positive | 1 | 3 |
| Diseased | Negative | 1 | 1 |
| Healthy | Positive | 1 | 0 |
| Healthy | Negative | 1 | 5 |
| Diseased | Positive | 2 | 24 |
| Diseased | Negative | 2 | 2 |
| Healthy | Positive | 2 | 2 |
| Healthy | Negative | 2 | 30 |
Frequency form dataset layout for 2 paired binary tests
Use a column for the true state variable (State), a column for each of the test indications (Test 1, Test 2) and a column for the number of cases (Frequency); each row has the values of the variables and the frequency count.
| State | Test 1 | Test 2 | Count |
|---|---|---|---|
| Diseased | Positive | Positive | 3 |
| Diseased | Negative | Positive | 1 |
| Diseased | Positive | Negative | 24 |
| Diseased | Negative | Negative | 2 |
| Healthy | Positive | Positive | 0 |
| Healthy | Negative | Positive | 5 |
| Healthy | Positive | Negative | 2 |
| Healthy | Negative | Negative | 30 |