DA0-002 Practice Exam 2 — 20 Questions

Question 1

In Tableau, you want to create a view showing the total sales per region, but also want to allow users to filter by year without losing the ability to see all regions. What feature should you use to compute the total sales that ignores the year filter?

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

Accepted Answer

LOD expression: { FIXED [Region] : SUM([Sales]) }. A Level of Detail (LOD) expression with FIXED can compute a value at the region level, ignoring other dimensions like year.

Answer

Table calculation running total

Answer

Parameter action

Answer

Calculated field using SUM([Sales])

Question 2

A company is merging two databases from different departments. In Database A, customer IDs are integers. In Database B, customer IDs are alphanumeric strings. To merge, the data analyst must reconcile these differences. Which step should be taken first?

Accepted Answer

Perform data profiling to understand the ID formats and relationships. Data profiling is the essential first step before any transformation or mapping. It allows the analyst to examine the actual formats, patterns, and relationships in both ID columns (e.g., whether Database B's alphanumeric IDs contain embedded numeric sequences or consistent prefixes). Without profiling, any conversion or mapping would be based on assumptions that could lead to data loss or incorrect merges.

Answer

Drop the ID column and use a surrogate key

Answer

Convert all IDs to integers using CAST

Answer

Create a mapping table based on the first character

Question 3

A data analyst needs to count the number of orders placed by each customer, but only for customers who have placed more than 5 orders. Which SQL clause should be used to filter the aggregated results?

Accepted Answer

HAVING. HAVING is used to filter groups after aggregation. The query would use GROUP BY customer_id, then HAVING COUNT(*) > 5.

Answer

FILTER

Answer

WHERE

Answer

LIMIT

Question 4

Given the linear regression output, which independent variable has the strongest effect on price, based on standardized coefficients?

Accepted Answer

sqft_living. Standardized coefficients (beta weights) allow comparison of the relative strength of independent variables by measuring the number of standard deviations the dependent variable changes per one standard deviation change in the predictor. In the regression output, sqft_living has the highest absolute standardized coefficient, indicating it has the strongest effect on price. The intercept is not an independent variable and its coefficient is not standardized for comparison.

Answer

bathrooms

Answer

Intercept

Answer

bedrooms

Question 5

Which THREE are best practices for acquiring data via web scraping? (Select exactly 3)

Accepted Answer

Respect robots.txt. Options B, C, and E are correct because best practices for web scraping include respecting robots.txt (ethical and legal compliance), identifying yourself with a user-agent (transparency), and limiting request rate (avoid overloading servers). Option A is incorrect because using multiple IP addresses is often used to circumvent blocking, which can violate terms of service and is not a recommended best practice. Option D is incorrect because scraping all data without regard to terms is unethical and potentially illegal.

Answer

Use multiple IP addresses

Answer

Scrape all data without regard to terms

Question 6

Which TWO of the following are commonly used techniques for handling missing data in a dataset? (Select TWO).

Accepted Answer

Mean imputation. Mean imputation is a commonly used technique for handling missing numerical data where the missing value is replaced with the mean of the observed values for that feature. It preserves the sample size and is simple to implement, though it can reduce variance and distort relationships if data is not missing completely at random.

Answer

Mode imputation

Answer

Dropping columns with missing data

Answer

Dropping rows with missing data

Question 7

A data analyst is extracting data from a relational database using SQL. Which clause is essential for limiting the rows retrieved to only those needed?

Accepted Answer

WHERE. WHERE. The WHERE clause is used to filter rows from a table based on specified conditions, limiting the result set to only the rows that meet those conditions. Option A (GROUP BY) is incorrect because it groups rows with same values into summary rows, not for filtering. Option B (ORDER BY) is incorrect because it sorts the result set, not filters. Option D (HAVING) is incorrect because it filters groups after aggregation, not individual rows. Therefore, WHERE is essential for limiting rows retrieved.

Answer

GROUP BY

Answer

ORDER BY

Answer

HAVING

Question 8

A financial analyst needs to show how net income is derived from revenue, costs, and expenses over a period. The chart should highlight the contribution of each component. Which chart type is most appropriate?

Accepted Answer

Waterfall chart. A waterfall chart shows how an initial value is affected by a series of positive and negative changes, making it ideal for financial breakdowns.

Answer

Line chart

Answer

Area chart

Answer

Pie chart

Question 9

A business analyst needs to explain to a sales director that the reported revenue has a 95% confidence interval of ±2%. Which concept is being communicated?

Accepted Answer

Uncertainty communication. Confidence intervals quantify the uncertainty around a metric, conveying that the true value may vary.

Answer

Data governance

Answer

Single version of truth

Answer

Data lineage

Question 10

A data analyst notices that customer addresses in the database contain invalid ZIP codes. Which data quality dimension is being violated?

Accepted Answer

Validity. A is correct because validity refers to the degree to which data conforms to its defined format, rules, or constraints. Invalid ZIP codes (e.g., a five-digit code containing letters or a non-existent postal code) directly violate the format and domain rules expected for that field, making this a validity issue.

Answer

Timeliness

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Consistency

Answer

Completeness

Question 11

A data analyst is designing a dashboard for executives. Which best practice should be followed regarding the placement of key performance indicators (KPIs)?

Accepted Answer

Place the most important KPIs in the top-left corner. Placing the most important KPIs in the top-left corner follows natural reading patterns (left-to-right, top-to-bottom), ensuring executives see critical metrics first. Option A is wrong because including too many charts on a single screen reduces readability and can overwhelm users. Option B is wrong because hiding KPIs behind filters defeats the purpose of having them visible at a glance. Option C is wrong because using distinct colors for all KPIs equally does not prioritize information; it may actually create visual clutter and reduce clarity.

Answer

Include as many charts as possible on a single screen to avoid scrolling

Answer

Hide KPIs behind filters to reduce initial load time

Answer

Use distinct colors to highlight all KPIs equally

Question 12

A data analyst wants to generate a report showing employee names and their department names, but some employees are not assigned to any department. The analyst wants to include all employees. Which JOIN type should be used?

Accepted Answer

LEFT JOIN. LEFT JOIN includes all rows from the left table (employees) even if no match in departments.

Answer

INNER JOIN

Answer

CROSS JOIN

Answer

RIGHT JOIN

Question 13

A data analyst needs to extract the year from a column named 'order_date' in a SQL database. The database supports standard SQL functions. Which function should they use?

Accepted Answer

EXTRACT(YEAR FROM order_date). The EXTRACT function is standard SQL for extracting date parts. EXTRACT(YEAR FROM order_date) returns the year.

Answer

GET_YEAR(order_date)

Answer

YEAR(order_date)

Answer

DATE_PART('year', order_date)

Question 14

A data analyst creates a dashboard that includes a map showing sales by region. The map uses a continuous color gradient from light yellow to dark blue. Some regions with very high sales appear as dark blue, but many regions with moderate sales appear similar. Which improvement would most enhance the readability?

Accepted Answer

Use a discrete color scale with distinct bins for sales ranges.. A discrete color scale with distinct bins for sales ranges eliminates the ambiguity caused by a continuous gradient, where moderate sales values blend together. By grouping sales into defined intervals (e.g., $0–$10K, $10K–$50K, etc.), each region is assigned a unique, easily distinguishable color, making it immediately clear which sales bracket a region falls into without requiring precise color differentiation.

Answer

Switch to a diverging color scheme with a neutral midpoint.

Answer

Increase the map size to show more detail.

Answer

Add data labels to each region showing exact sales numbers.

Question 15

In a logistic regression model predicting customer churn (1 = churn, 0 = not churn), the coefficient for 'contract length' is -0.5. Which of the following is the correct interpretation?

Accepted Answer

For each unit increase in contract length, the log-odds of churn decrease by 0.5.. In logistic regression, coefficients represent the log-odds change. A negative coefficient decreases the log-odds, meaning lower probability of churn.

Answer

Longer contract length increases the odds of churn.

Answer

The probability of churn decreases by 50% for each unit increase in contract length.

Answer

Contract length is not a significant predictor.

Question 16

A retail company has a dashboard that tracks daily sales across all stores. The dashboard is used by the CEO during monthly board meetings. Recently, the CEO complained that the dashboard is confusing and takes too long to interpret. The data analyst is asked to redesign the dashboard to improve usability. The analyst has access to all sales data. The CEO prefers a high-level overview with the ability to drill down into regions if needed. The analyst must decide on a course of action. What should the analyst do first?

Accepted Answer

Interview the CEO to determine key performance indicators and preferred layout.. The correct first step is to interview the CEO to determine key performance indicators and preferred layout. This ensures the dashboard is designed around the specific high-level metrics the CEO needs for monthly board meetings, with the ability to drill down into regions. Starting with stakeholder requirements prevents wasted effort on irrelevant visualizations or formats.

Answer

Revamp the dashboard with as many visualizations as possible.

Answer

Conduct a survey of all employees to understand their needs.

Answer

Create a static PDF report instead of a dashboard.

Question 17

A data engineer is designing an ETL pipeline to extract sales data from a legacy on-premise database and load it into a cloud data warehouse. The database is slow and queries during business hours affect performance. Which extraction strategy minimizes impact?

Accepted Answer

Incremental extraction using Change Data Capture (CDC). Incremental extraction using Change Data Capture (CDC) minimizes impact on the legacy on-premise database by reading only the changed rows (inserts, updates, deletes) from transaction logs or change tables, rather than issuing heavy SELECT queries. This avoids full table scans or frequent queries during business hours, preserving database performance for operational workloads.

Answer

Query the database with SELECT * every hour

Answer

Full table extraction nightly

Answer

Use a database log shipping

Question 18

Which TWO of the following are examples of supervised learning algorithms?

Accepted Answer

Linear regression. Linear regression is a supervised learning algorithm because it learns a mapping from input features to a continuous target variable using labeled training data. The model minimizes the difference between predicted and actual values (e.g., via ordinary least squares) to make predictions on new data.

Answer

K-means clustering

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Principal component analysis (PCA)

Answer

Apriori algorithm

Question 19

Which THREE of the following are assumptions of linear regression? (Select THREE).

Accepted Answer

Independence of errors. Independence of errors is a core assumption of linear regression, meaning the residuals (errors) should not be correlated with each other. This is critical for valid inference because correlated errors violate the Gauss-Markov theorem, leading to biased standard errors and unreliable hypothesis tests. In time series data, this assumption is often violated due to autocorrelation, which can be detected using the Durbin-Watson test.

Answer

Normal distribution of independent variables

Answer

Multicollinearity among independent variables

Question 20

A data analyst frequently receives ad hoc requests for the same type of analysis. Which TWO approaches could reduce the number of ad hoc requests?

Accepted Answer

Create a scheduled report that covers the common analysis. Building self-service capabilities and iterating on feedback to improve scheduled reports can address recurring needs and reduce ad hoc requests.

Answer

Increase data freshness to real-time

Answer

Add more security to the data

Answer

Ignore the requests until they become urgent