DA0-002 Practice Test 32 — 15 Questions

Question 1

A data analyst is building a binary classification model to predict customer churn. The dataset is imbalanced, with only 10% churners. The analyst wants to evaluate model performance with a focus on correctly identifying churners. Which metric is most appropriate?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Recall (sensitivity). Recall (sensitivity) is the most appropriate metric because it measures the proportion of actual churners correctly identified by the model. Since the dataset is imbalanced (only 10% churners) and the analyst's focus is on correctly identifying churners, recall directly addresses the cost of missing positive cases (false negatives). Accuracy would be misleading due to class imbalance, while precision and F1-score prioritize different trade-offs.

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F1-score

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Precision

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Accuracy

Question 2

The exhibit shows log entries. A data analyst wants to visualize the frequency of each error type over time. Which chart type is most appropriate?

Accepted Answer

Time series line chart. A time series line chart counts events per time interval, best for showing frequency over time. Bar chart of counts is static. Pie of error types ignores time. Scatter plot not suitable.

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Bar chart of error types

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Scatter plot of timestamp vs error code

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Pie chart of error types

Question 3

An analyst is creating a report that includes multiple charts. To ensure the audience quickly grasps the key insight, which principle of data storytelling should be applied?

Accepted Answer

Use a title that states the main insight. Starting with a clear title that summarizes the takeaway guides the audience to the main insight. Using a legend only or placing the chart first does not provide context. Avoiding titles reduces clarity.

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Avoid using titles to reduce clutter

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Include a legend for every chart

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Place the chart before any explanation

Question 4

A data scientist is building a predictive model to forecast monthly sales. The data shows a linear trend with no seasonality. Which regression technique is most appropriate?

Accepted Answer

Linear regression. Linear regression is the most appropriate technique because the data shows a linear trend with no seasonality, making a straight-line model the simplest and most effective fit. It directly models the relationship between the independent variable (e.g., time) and the dependent variable (monthly sales) using a linear equation, minimizing the sum of squared residuals.

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Polynomial regression

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Logistic regression

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Ridge regression

Question 5

Which TWO visualization types are suitable for showing the distribution of a single continuous variable?

Accepted Answer

Box plot. A box plot is correct because it graphically depicts the distribution of a single continuous variable through its five-number summary (minimum, first quartile, median, third quartile, maximum), clearly showing spread, central tendency, and outliers. A histogram is correct because it bins the continuous variable into intervals and displays the frequency of data points within each bin, providing a direct view of the underlying probability distribution.

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Line chart

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Scatter plot

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Pie chart

Question 6

A data analyst is tasked with visualizing the distribution of customer ages across different regions. The dataset contains outliers. Which chart type best displays the distribution and highlights outliers?

Accepted Answer

Box plot. A box plot explicitly shows median, quartiles, and outliers, making it ideal for distribution and outlier detection. Histogram shows distribution but not outliers clearly. Violin plot is similar but more complex. Bar chart is not for distribution.

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Violin plot

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Histogram

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Bar chart

Question 7

A social media monitoring company collects public tweets using the Twitter API. The API has a tiered access: free tier allows 500,000 tweets per month, and paid tier allows 2 million tweets per month. The company needs to collect 1.5 million tweets per month for analysis. They are on a free tier but have been exceeding the limit, causing account suspension. They need a sustainable solution without significantly increasing costs. What should they do?

Accepted Answer

Use multiple developer accounts to stay within free limits. Using multiple developer accounts to distribute the collection load can allow access to more tweets while staying within each account's free limit. This avoids the cost of upgrading to a paid tier. Reducing collection to 500,000 tweets would cause loss of critical data. Requesting an academic exemption is unlikely because the company is commercial. Upgrading to paid tier increases costs significantly.

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Request an academic research exemption

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Reduce the collection to exactly 500,000 tweets per month by sampling

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Upgrade to the paid tier

Question 8

A data architect is designing an ETL pipeline to ingest streaming data from IoT sensors. The data must be available for real-time analytics. Which acquisition method is best?

Accepted Answer

Real-time streaming via API. Real-time streaming via API is the best method because IoT sensors generate continuous data that must be ingested with sub-second latency for real-time analytics. APIs (e.g., REST, WebSocket, or MQTT) enable event-driven ingestion, allowing the ETL pipeline to process each sensor reading as it arrives, which is essential for time-sensitive use cases like anomaly detection or live monitoring.

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Poll sensors every hour

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Manually upload sensor logs

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Batch load daily CSV files

Question 9

A data analyst is building a dataset from multiple sources and needs to ensure data quality. During the data acquisition phase, which activity is most important to perform?

Accepted Answer

Data profiling. Data profiling is the most important activity during the data acquisition phase because it involves examining source data to understand its structure, content, and quality issues before integration. This step identifies missing values, data types, duplicates, and inconsistencies early, preventing downstream errors in analysis. Without profiling, subsequent cleaning and modeling may be based on flawed assumptions about the data.

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Data visualization

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Data cleaning

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Data modeling

Question 10

An executive dashboard needs to display key performance indicators (KPIs) such as sales growth and customer satisfaction. Which design principle is most important?

Accepted Answer

Consistent color encoding for similar metrics. Consistent color coding helps viewers quickly associate colors with metrics across multiple charts.

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Use gauges for each KPI

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Include all raw data in the dashboard

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Animate charts to draw attention

Question 11

Which THREE data sources are suitable for web scraping? (Select three.)

Accepted Answer

HTML pages. HTML pages are suitable for web scraping because they contain structured or semi-structured data in markup format that can be parsed using libraries like BeautifulSoup or Scrapy. Web scrapers extract information from the DOM tree by targeting specific tags, classes, or attributes, making HTML a primary source for scraping.

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CSV files

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Database connections

Question 12

A heat map of store sales by region shows very low correlation between advertising spend and revenue, but a scatter plot of the same data shows a strong positive relationship. What is the most likely cause?

Accepted Answer

Data was aggregated incorrectly in the heat map. Heat maps often aggregate data into bins (e.g., averages), which can mask the underlying relationship.

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The heat map used an incorrect color scale

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Outliers were removed only for the scatter plot

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The chart types are inherently incompatible

Question 13

Which TWO are common methods for acquiring internal data? (Choose two.)

Accepted Answer

Transaction logs. Transaction logs are a primary source of internal data because they record every interaction or event within a system, such as database changes, user access, or application errors. This data is generated and stored internally by the organization's own infrastructure, making it a classic example of internal data acquisition.

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Social media APIs

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Government databases

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Web scraping

Question 14

A company wants to collect real-time clickstream data from its website. Which acquisition method is most suitable?

Accepted Answer

Streaming API. A streaming API is the most suitable method for collecting real-time clickstream data because it enables continuous, low-latency ingestion of events as they occur. Unlike batch or manual methods, a streaming API (e.g., using WebSockets or HTTP/2 Server-Sent Events) pushes each click event immediately to the data pipeline, satisfying the real-time requirement.

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Web scraping

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Batch processing nightly

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Manual entry

Question 15

Which TWO are examples of internal data sources? (Select exactly 2)

Accepted Answer

Relational databases. Relational databases are internal data sources because they store structured data generated and controlled within an organization's own systems. They are typically managed by internal IT teams and accessed via SQL queries, making them a classic example of an internal data repository.

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APIs

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Sensor readings

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Social media comments