MLA-C01 Data Preparation for Machine Learning Practice Question
A company collects sensor data from IoT devices. The data arrives with missing timestamps due to network issues. For anomaly detection, the engineer needs to create features that capture rolling statistics over fixed windows. Which data preprocessing step is essential before feature generation?
⚠ Common exam trap
AWS often tests the distinction between handling missing values (imputation) and handling irregular timestamps (resampling), leading candidates to confuse forward-fill as a solution for time alignment when it only addresses missing data points, not the underlying time index irregularity.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Resample data to a fixed frequency
Resampling the data to a fixed frequency is essential because rolling window statistics require a consistent time index to compute accurate aggregations over fixed windows. Without a uniform timestamp grid, the window boundaries become ambiguous and the resulting features will be misaligned or incomplete, undermining the anomaly detection model.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Remove missing timestamps
Why it's wrong here
Removing timestamps can break continuity but does not create regular intervals.
- ✓
Resample data to a fixed frequency
Why this is correct
Resampling ensures consistent time intervals, which is required for rolling windows.
- ✗
Sort data by device ID
Why it's wrong here
Sorting is important but does not address the irregular time intervals.
- ✗
Impute missing values with forward fill
Why it's wrong here
Imputation fills gaps but does not create regular timestamps; resampling is needed first.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MLA-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 MLA-C01 exam.