DA0-001 Mining and Acquiring Data Practice Question
This DA0-001 practice question tests your understanding of mining and acquiring data. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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.
During a data mining project, an analyst discovers that a significant number of records have a negative value for the age field. What is the most appropriate first step?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Investigate the source system for data entry errors.
Option C is correct because the first step in handling anomalous data like negative ages is to investigate the source system for data entry errors. This aligns with the data mining process, where understanding the root cause of data quality issues is critical before applying any imputation or removal techniques. Without investigation, you risk masking systemic problems that could affect all records.
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.
✗
Impute using regression.
Why it's wrong here
Regression imputation is premature without understanding the data quality issue.
✗
Replace negative age with the mean age.
Why it's wrong here
Imputation should follow root cause analysis to avoid masking data quality problems.
✓
Investigate the source system for data entry errors.
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Remove all records with negative age.
Why it's wrong here
Removing data without investigation can discard valuable information and hides underlying issues.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often jump to data cleaning techniques like imputation or removal without first verifying whether the anomaly is a data quality issue or a legitimate value, which the DA0-001 exam tests by emphasizing the investigative step as the most appropriate first action.
Detailed technical explanation
How to think about this question
In data mining, the CRISP-DM framework emphasizes data understanding and cleaning as iterative steps; investigating source systems often involves checking input validation rules, database constraints, or ETL pipelines that may have allowed negative values for age. For example, a real-world scenario might involve a legacy system that stored age as a signed integer without range checks, causing negative values when a date calculation overflowed. This investigation could reveal a need for constraints like CHECK (age >= 0) in SQL or validation in the application layer.
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.
TExam Day Tips
→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 network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Mining and Acquiring Data — This question tests Mining and Acquiring Data — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Investigate the source system for data entry errors. — Option C is correct because the first step in handling anomalous data like negative ages is to investigate the source system for data entry errors. This aligns with the data mining process, where understanding the root cause of data quality issues is critical before applying any imputation or removal techniques. Without investigation, you risk masking systemic problems that could affect all records.
What should I do if I get this DA0-001 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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