DA0-002 Practice Test 35 — 15 Questions

Question 1

Refer to the exhibit. A data analyst receives this error when running a data load script. What is the most likely cause?

Accepted Answer

The customer_id 12345 already exists in the table. The error message states 'Duplicate entry '12345' for key 'PRIMARY'', indicating that a record with customer_id 12345 already exists in the table. Option A (email too long) would produce a data truncation error, not a duplicate key error. Option B (connection lost) would result in a connection timeout or similar error. Option D (name field null) could cause a constraint violation if the column is not nullable, but the specific error here is a primary key violation.

Answer

The email field is too long

Answer

The database connection is lost

Answer

The name field is null

Question 2

A data analyst is creating a presentation for the board of directors. The board members have varying levels of data literacy. The analyst wants to ensure that the key insight—that customer satisfaction scores have declined by 15% due to longer wait times—is understood by everyone. Which approach is best?

Accepted Answer

Use a simple annotated line chart with a clear callout on the decline.. A simple annotated line chart with a clear callout on the decline is intuitive and draws attention to the key insight. Options A, B, and C are either too complex or not focused.

Answer

Include a complex statistical model showing the correlation.

Answer

Show a scatter plot of wait time vs. satisfaction.

Answer

Provide raw data in a spreadsheet for review.

Question 3

A sales analyst is designing a report for the sales team that includes the number of new leads, conversion rate, and total revenue. The team wants to identify which metrics are Key Performance Indicators (KPIs) tied to the strategic goal of increasing revenue. Which TWO of the following should be classified as KPIs?

Accepted Answer

Total revenue. Total revenue is a direct measure of the strategic goal of increasing revenue, making it a clear Key Performance Indicator (KPI). It quantifies the financial outcome that the sales team is aiming to improve, aligning perfectly with the stated objective.

Answer

Average deal size

Answer

Customer satisfaction score

Answer

Number of new leads

Question 4

A data team is designing an ETL process to extract data from an operational database daily. The database experiences heavy write loads during business hours. What is the best practice to minimize impact on operations?

Accepted Answer

Use replication or a read replica to extract data. (use replication or a read replica) is best because it offloads the extraction from the primary database, minimizing impact on operational write loads. Option A extracts directly from the primary, impacting performance. Option B runs extraction during peak hours, which increases load and negatively affects operations. Option C still extracts from the primary even at midnight, though less busy, it still adds load to the primary.

Answer

Extract directly from the primary database with high priority

Answer

Run the extraction during peak hours to ensure data freshness

Answer

Schedule extraction at midnight when load is low

Question 5

A data scientist is building a classification model to predict customer churn. The dataset has 10,000 records with 500 churners. The scientist uses logistic regression and achieves 98% accuracy, but the precision for churn class is only 15%. Which of the following is the most likely cause?

Accepted Answer

Class imbalance. The dataset has only 500 churners out of 10,000 records (5% churn rate), which is a classic class imbalance. Logistic regression can achieve high accuracy by simply predicting the majority class (non-churn) for all records, yielding 95% accuracy even without learning anything about churn. The very low precision (15%) for the churn class indicates that most of the positive predictions are false positives, a direct consequence of the model being biased toward the majority class due to imbalance.

Answer

Non‑linear decision boundary

Answer

Multicollinearity among predictor variables

Answer

Overfitting due to too many features

Question 6

A data scientist is merging retail transaction data from online and in-store sources. Which THREE steps are required to ensure data consistency?

Accepted Answer

Ensure product IDs are standardized across sources. Options A (standardize product IDs), B (convert monetary amounts to a common currency), and D (synchronize timestamps to a single time zone) are essential for data consistency when merging online and in-store transaction data. Option C (remove all transactions with missing customer ID) is not required and may discard useful data; missing customer IDs can be handled in other ways. Option E (merge using only store location) is insufficient as it ignores other identifiers and may cause mismatches.

Answer

Remove all transactions with missing customer ID

Answer

Merge data using only store location

Question 7

A data analyst needs to combine sales data from multiple regional databases with different schemas. Which process is best?

Accepted Answer

ETL (Extract, Transform, Load). ETL (Extract, Transform, Load) is designed to extract data from various sources, transform it to a common schema, and load it into a target system. Option A (Data federation) is wrong because it provides virtual integration without transforming data into a consistent schema. Option C (Data replication) is wrong because it copies data without transformation. Option D (Data virtualization) is wrong because it provides real-time access to disparate sources without physically storing the transformed data.

Answer

Data federation

Answer

Data replication

Answer

Data virtualization

Question 8

A financial analyst is integrating data from multiple stock exchanges. One exchange provides trade timestamps in UTC, another in Eastern Time. The analyst needs accurate time synchronization for time-series analysis. What is the best approach?

Accepted Answer

Convert all timestamps to a single timezone (e.g., UTC) during ETL. (convert to UTC) is the standard. Option A (keep original with offset) adds complexity. Option B (local time) is inconsistent. Option D (ignore) leads to errors.

Answer

Keep original timezones and add a timezone offset column

Answer

Use the local time of the analyst's location

Answer

Ignore timezone differences if analysis is intraday

Question 9

A time series dataset has several missing months of data. Which chart type will present the most honest picture of the trend?

Accepted Answer

Line chart with gaps for missing months. Line charts with gaps explicitly show missing periods, avoiding false continuity.

Answer

Area chart with interpolation

Answer

Bar chart with zero values for missing months

Answer

Scatter plot with connected lines

Question 10

A company uses a dashboard to monitor server uptime. The data is collected every minute, but the dashboard only refreshes every hour. Users see gaps in the line chart. What is the most likely cause, and how should it be fixed?

Accepted Answer

Increase the dashboard refresh rate to match data collection frequency. The gaps occur because the dashboard aggregates data over one-hour intervals, while data is collected every minute. When the dashboard refreshes, it only shows the latest one-hour snapshot, so data between refreshes is missing. Increasing the dashboard refresh rate to match data collection frequency ensures continuous display. Interpolation (option A) would artificially fill gaps, masking the issue rather than fixing it; the correct solution is to align refresh rates.

Answer

The line chart should interpolate missing data points

Answer

Switch to a bar chart to avoid gaps

Answer

Use a different data series with the same refresh rate

Question 11

A data analyst is designing a dashboard for executives. Which best practice should be followed?

Accepted Answer

Minimize clutter and use clear visual hierarchy. Reducing clutter helps viewers focus on key insights without distraction.

Answer

Use 3D effects to make charts more engaging

Answer

Include every data point in the dashboard

Answer

Use rainbow color palette to highlight all data points

Question 12

A data analyst reports being unable to run the query shown in the exhibit. The data governance team reviews the access control policy. Which of the following is the most likely explanation for the denied access?

Accepted Answer

Column-level security is preventing access to the email column. The log explicitly states 'insufficient permissions on column email', indicating column-level security. Option A is wrong because the log does not mention table-level privilege issues. Option B is wrong because the role status is not indicated in the log. Option D is wrong because the query syntax is correct.

Answer

The user does not have SELECT privilege on the customers table

Answer

The database administrator revoked the analyst role

Answer

The query syntax is incorrect

Question 13

A company needs to visualize monthly sales revenue for the past five years to identify seasonal trends. Which chart type is most appropriate?

Accepted Answer

Line chart with months on the x-axis and revenue on the y-axis. (Line chart) is correct because line charts are ideal for showing trends over time, such as monthly sales revenue over five years. Option B (Stacked bar chart) would segment each year, making it harder to see continuous trends. Option C (Scatter plot) is for relationships between two variables, not time series trends. Option D (Pie chart) is for proportions, not trends over time.

Answer

Stacked bar chart showing each year as a segment

Answer

Scatter plot with revenue vs. month number

Answer

Pie chart for each year showing revenue distribution

Question 14

A business analyst wants to compare the proportion of total sales contributed by each product category in the current year. Which visualization is most suitable?

Accepted Answer

Pie chart. A pie chart effectively shows the proportion of each category as part of a whole, which is ideal for comparing the contribution of each product category to total sales. Option B (scatter plot) is used to show relationships between two variables, not proportions. Option C (line chart) is best for trends over time. Option D (histogram) shows the distribution of a continuous variable.

Answer

Scatter plot

Answer

Line chart

Answer

Histogram

Question 15

Which TWO are common mistakes when creating data visualizations?

Accepted Answer

Using excessive 3D effects that obscure data. Options A and E are correct. Excessive 3D effects (A) can obscure or distort data, and truncating the y-axis (E) can mislead viewers by exaggerating differences. Option B is incorrect because sorting alphabetically can aid lookup, not a mistake. Option C is incorrect because color-blind friendly palettes are a best practice, not a mistake. Option D is incorrect because including a legend is standard good practice.

Answer

Sorting categories alphabetically in a bar chart

Answer

Choosing a color-blind friendly palette

Answer

Including a legend to identify chart elements