Interpret Precision Recall Tradeoff | Dataford Interview Questions

Context

MediScan built a binary classifier to flag chest X-rays for possible pneumonia so radiologists can prioritize urgent cases. The model is now in production, but hospital leadership is concerned that the team is focusing on the wrong metric when deciding whether to adjust the decision threshold.

Current Performance

Metric	Validation Set	Notes
Precision	0.91	91% of flagged scans are true pneumonia cases
Recall	0.68	68% of all pneumonia cases are detected
F1 Score	0.78	Harmonic mean of precision and recall
Accuracy	0.95	High due to class imbalance
AUC-ROC	0.89	Good ranking ability overall
Positive class prevalence	8%	Pneumonia is relatively rare

At the current threshold, the confusion matrix on 10,000 labeled scans is:

	Predicted Positive	Predicted Negative
Actual Positive	544	256
Actual Negative	54	9,146

The Problem

The radiology operations lead wants fewer false alarms to reduce unnecessary urgent reviews, while the chief medical officer is more concerned about missed pneumonia cases. You need to explain the difference between precision and recall using the model's actual results and recommend how the team should reason about threshold changes.

Requirements

Define precision and recall using the numbers above, not just textbook formulas.
Explain what each metric says about model behavior in this clinical setting.
Discuss why accuracy alone is misleading here.
Recommend whether MediScan should optimize more for precision or recall and justify the tradeoff.
Suggest practical next steps to improve the model without overwhelming radiologists.

Constraints

Missing a true pneumonia case can delay treatment.
Too many false positives increase radiologist workload.
The review team can handle at most 750 urgent flags per day.

Problem

Context

Current Performance

Metric	Validation Set	Notes
Precision	0.91	91% of flagged scans are true pneumonia cases
Recall	0.68	68% of all pneumonia cases are detected
F1 Score	0.78	Harmonic mean of precision and recall
Accuracy	0.95	High due to class imbalance
AUC-ROC	0.89	Good ranking ability overall
Positive class prevalence	8%	Pneumonia is relatively rare

At the current threshold, the confusion matrix on 10,000 labeled scans is:

	Predicted Positive	Predicted Negative
Actual Positive	544	256
Actual Negative	54	9,146

The Problem

Requirements

Define precision and recall using the numbers above, not just textbook formulas.
Explain what each metric says about model behavior in this clinical setting.
Discuss why accuracy alone is misleading here.
Recommend whether MediScan should optimize more for precision or recall and justify the tradeoff.
Suggest practical next steps to improve the model without overwhelming radiologists.

Constraints

Missing a true pneumonia case can delay treatment.
Too many false positives increase radiologist workload.
The review team can handle at most 750 urgent flags per day.

Problem

Context

Current Performance

Metric	Validation Set	Notes
Precision	0.91	91% of flagged scans are true pneumonia cases
Recall	0.68	68% of all pneumonia cases are detected
F1 Score	0.78	Harmonic mean of precision and recall
Accuracy	0.95	High due to class imbalance
AUC-ROC	0.89	Good ranking ability overall
Positive class prevalence	8%	Pneumonia is relatively rare

At the current threshold, the confusion matrix on 10,000 labeled scans is:

	Predicted Positive	Predicted Negative
Actual Positive	544	256
Actual Negative	54	9,146

The Problem

Requirements

Define precision and recall using the numbers above, not just textbook formulas.
Explain what each metric says about model behavior in this clinical setting.
Discuss why accuracy alone is misleading here.
Recommend whether MediScan should optimize more for precision or recall and justify the tradeoff.
Suggest practical next steps to improve the model without overwhelming radiologists.

Constraints

Missing a true pneumonia case can delay treatment.
Too many false positives increase radiologist workload.
The review team can handle at most 750 urgent flags per day.

Problem

Context

Current Performance

Metric	Validation Set	Notes
Precision	0.91	91% of flagged scans are true pneumonia cases
Recall	0.68	68% of all pneumonia cases are detected
F1 Score	0.78	Harmonic mean of precision and recall
Accuracy	0.95	High due to class imbalance
AUC-ROC	0.89	Good ranking ability overall
Positive class prevalence	8%	Pneumonia is relatively rare

At the current threshold, the confusion matrix on 10,000 labeled scans is:

	Predicted Positive	Predicted Negative
Actual Positive	544	256
Actual Negative	54	9,146

The Problem

Requirements

Define precision and recall using the numbers above, not just textbook formulas.
Explain what each metric says about model behavior in this clinical setting.
Discuss why accuracy alone is misleading here.
Recommend whether MediScan should optimize more for precision or recall and justify the tradeoff.
Suggest practical next steps to improve the model without overwhelming radiologists.

Constraints

Missing a true pneumonia case can delay treatment.
Too many false positives increase radiologist workload.
The review team can handle at most 750 urgent flags per day.