An analyst runs a Python script that joins two CSV files on a customer ID column. The script fails with the error 'ValueError: You are trying to merge on object and int64 columns'. The analyst confirms both files contain the same customer IDs. What should the analyst do first to resolve this issue?

Rename the customer ID column to be identical in both DataFrames

Drop duplicate customer IDs from both files before merging

Cast the customer ID column in both DataFrames to the same data type (e.g., string) and re-run the merge

Use the 'on' parameter instead of 'left_on' and 'right_on' in the merge function

A marketing analyst is troubleshooting a dashboard that shows a sudden spike in new user sign-ups. The analyst suspects a data issue but must also consider if the spike is real (e.g., a successful campaign). What is the most systematic next step?

Cross-reference the sign-up timestamps with the timing of any recent marketing campaigns or external events

Immediately delete the data for the spike period to ensure the dashboard is not misleading

Change the dashboard's time range to hide the spike and avoid questions from stakeholders

Assume the spike is a data error and spend all effort looking for a bug in the ETL pipeline

An analyst needs to perform a quick, ad-hoc analysis on a dataset with a few thousand rows to find the median and standard deviation of a key metric. The analyst is most comfortable with spreadsheet software. Which tool is the most appropriate for this task?

Spreadsheet software, as it is well-suited for quick, interactive analysis on small to medium-sized datasets

A dedicated data visualization tool, as it is the best for calculating statistics

A custom Python script, as it is the only reliable way to calculate these statistics

A big data processing framework, as it is the most powerful tool available

An analyst is using a spreadsheet to clean a dataset and notices that the VLOOKUP function is returning '#N/A' for some records. The analyst has confirmed the lookup value exists in the table array. What is the most likely cause of this issue?

The spreadsheet application is corrupted and needs to be reinstalled

The analyst is using the wrong column index number in the VLOOKUP function

The dataset has too many rows for VLOOKUP to handle

The lookup value is a number stored as text, or the table array is not sorted in ascending order (if using approximate match)

An analyst needs to quickly inspect the distribution of a large dataset to check for unexpected values before running further analysis. Which tool is most appropriate for this initial troubleshooting step?

A relational database management system (RDBMS)

CompTIAData+

Domain 3Objective 3

Troubleshoot Analysis Issues DA0-001 Practice Questions (Page 3)

Part of the Data analysis domain, which accounts for 24% of the DA0-001 exam. CompTIA does not publish an official question count, but from its 90-minute exam (~35–60 total, ~8–14 in this domain), expect 3–5 from this objective — we provide 32 practice questions to prepare you well beyond it. (estimate)

32questions here

7free pages

7concepts

24%of the exam

Questions 11–15

11application · medium
An analyst runs a Python script that joins two CSV files on a customer ID column. The script fails with the error 'ValueError: You are trying to merge on object and int64 columns'. The analyst confirms both files contain the same customer IDs. What should the analyst do first to resolve this issue?
Select an answer first
12expert · hard
A marketing analyst is troubleshooting a dashboard that shows a sudden spike in new user sign-ups. The analyst suspects a data issue but must also consider if the spike is real (e.g., a successful campaign). What is the most systematic next step?
Select an answer first
13application · medium
An analyst needs to perform a quick, ad-hoc analysis on a dataset with a few thousand rows to find the median and standard deviation of a key metric. The analyst is most comfortable with spreadsheet software. Which tool is the most appropriate for this task?
Select an answer first
14application · medium
An analyst is using a spreadsheet to clean a dataset and notices that the VLOOKUP function is returning '#N/A' for some records. The analyst has confirmed the lookup value exists in the table array. What is the most likely cause of this issue?
Select an answer first
15foundation · easy
An analyst needs to quickly inspect the distribution of a large dataset to check for unexpected values before running further analysis. Which tool is most appropriate for this initial troubleshooting step?
Select an answer first

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