The answer is to increase recall, because the model currently captures only 20% of actual churners, leaving 80% undetected. In an imbalanced classifier with a 5% positive class, recall measures how many true churners the model successfully identifies, and a score of 0.2 indicates the model is failing its primary goal. Precision is already high at 0.8, so the bottleneck is not false positives but missed positives, making recall the metric to prioritize. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of how class imbalance distorts accuracy and why recall is the critical lever when false negatives are costly—a common trap is to chase F1 score, but the question explicitly asks for the metric to improve, not to balance. Remember the churn detection mantra: when the positive class is rare and missing it hurts, always increase recall first.
MLS-C01 Modeling Practice Question
This MLS-C01 practice question tests your understanding of modeling. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is building a binary classifier to predict customer churn. The dataset has 10,000 samples with 500 churners (5% positive class). After training a logistic regression model, the precision is 0.8 and recall is 0.2. Which metric should the data scientist focus on to improve the model's ability to identify churners while minimizing false positives?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase recall
Option A is correct because recall is very low (0.2), meaning the model misses most churners. Improving recall will capture more churners. Option B (precision) is already high but recall is low. Option C (accuracy) is misleading due to class imbalance. Option D (F1) balances precision and recall, but the primary concern is low recall.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Increase accuracy
Why it's wrong here
Accuracy is misleading due to class imbalance; a model that predicts majority class can have high accuracy.
✗
Increase precision
Why it's wrong here
Precision is already 0.8, which is acceptable; low recall is the main issue.
✓
Increase recall
Why this is correct
Recall is low (0.2), so improving it will capture more churners.
Related concept
Read the scenario before looking for a memorised answer.
✗
Increase F1 score
Why it's wrong here
F1 is a harmonic mean; improving recall will also improve F1, but the direct goal is recall.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which MLS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Modeling — This question tests Modeling — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase recall — Option A is correct because recall is very low (0.2), meaning the model misses most churners. Improving recall will capture more churners. Option B (precision) is already high but recall is low. Option C (accuracy) is misleading due to class imbalance. Option D (F1) balances precision and recall, but the primary concern is low recall.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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This MLS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MLS-C01 exam.
Question Discussion
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