DA0-002 Practice Test 27 — 15 Questions

Question 1

A data pipeline log shows the above error. Which data transformation should be applied during acquisition?

Accepted Answer

Preprocess the string to remove non-numeric characters, then convert to DECIMAL. The error indicates that the pipeline encountered a string with non-numeric characters (e.g., '$1,234.56') when trying to load it into a DECIMAL column. Preprocessing the string to remove non-numeric characters (like currency symbols, commas) before conversion ensures the data is clean and parseable, which is a standard data transformation during acquisition to handle dirty source data.

Answer

Skip rows that cause errors

Answer

Use CAST(transaction_amount AS DECIMAL(10,2)) in SQL

Answer

Change the target column type to VARCHAR

Question 2

Which TWO of the following are considered internal data sources within an organization?

Accepted Answer

Employee payroll data. Employee payroll data (B) is generated and stored internally by an organization's HR or finance systems, making it an internal data source. Sales transaction records (D) are also generated internally through the organization's sales processes. Both are proprietary and not accessible from outside, fitting the definition of internal data. In contrast, social media feeds (A), government census data (C), and third-party market research (E) originate externally and are therefore external data sources.

Answer

Social media feeds

Answer

Government census data

Answer

Market research reports from third parties

Question 3

A sensor records temperature readings in Celsius and a separate sensor records wind speed in meters per second. A data scientist wants to combine these datasets for analysis. Which statement accurately compares these data types?

Accepted Answer

Temperature is interval; wind speed is ratio. Temperature measured in Celsius has an arbitrary zero point (0°C does not mean 'no heat'), so it is interval data. Wind speed in meters per second has a true zero point (0 m/s means no wind), making it ratio data. Therefore, option D correctly identifies temperature as interval and wind speed as ratio.

Answer

Both are ratio data

Answer

Temperature is discrete; wind speed is continuous

Answer

Both are discrete data

Question 4

A data analyst is preparing a presentation for a mixed audience of executives and technical staff. Which two of the following practices would be most effective? (Select TWO.)

Accepted Answer

Provide a detailed appendix for technical staff.. A detailed appendix allows technical staff to access granular data, methodology, and supporting statistics without overwhelming the executive audience. This practice aligns with the principle of audience segmentation in data communication, ensuring that each stakeholder group receives the appropriate level of detail without disrupting the presentation flow.

Answer

Use only text-heavy slides to include all details.

Answer

Avoid any data visualizations to prevent confusion.

Answer

Use complex statistical terms without explanation.

Question 5

An analyst is creating a data story about the decline in customer satisfaction scores. The data shows that satisfaction dropped after a software update. Which narrative structure best helps the audience understand the cause and effect?

Accepted Answer

Begin with the software update event, then show satisfaction before and after. It follows a chronological cause-and-effect narrative, starting with the software update event and then showing satisfaction scores before and after. This structure directly maps to the audience's need to understand the causal relationship, as it highlights the intervention point and the resulting change in the metric. In data storytelling, this is known as the 'before-and-after' or 'change-over-time' narrative, which is most effective for demonstrating impact.

Answer

Start with the current scores, then show historical trend

Answer

Present all data points without a story

Answer

Use a pie chart of satisfaction categories

Question 6

An analyst computed the mean, median, and mode of a dataset and found they are all equal. Which of the following best describes the distribution?

Accepted Answer

Symmetric. When mean, median, and mode are equal, the distribution is symmetric and unimodal, often resembling a normal distribution.

Answer

Bimodal

Answer

Negatively skewed

Answer

Positively skewed

Question 7

A financial analyst is building a model to predict stock price movements. The data is time series with daily prices. The analyst wants to use a regression model but notices that the residuals are autocorrelated. What adjustment should be made?

Accepted Answer

Use a time series model like ARIMA instead. When residuals from a regression model on time series data exhibit autocorrelation, the standard ordinary least squares (OLS) assumptions are violated, leading to biased standard errors and unreliable inference. An ARIMA model is specifically designed to handle autocorrelated time series by explicitly modeling the autoregressive (AR) and moving average (MA) components, making it the correct adjustment to capture the temporal dependencies in stock price movements.

Answer

Use cross-validation to validate the model

Answer

Add more predictors to the regression model

Answer

Transform the data to remove autocorrelation (e.g., differencing)

Question 8

An analyst wants to visualize the relationship between advertising spend (x-axis) and revenue (y-axis) for 100 different products. Each product is in one of three categories. Which chart type best displays this data?

Accepted Answer

Scatter plot with points colored by category. A scatter plot with color-coded categories effectively shows relationships between two continuous variables and a third categorical dimension.

Answer

Bubble chart

Answer

Stacked bar chart

Answer

Line chart with three lines

Question 9

Drag and drop the steps for the ETL (Extract, Transform, Load) process in the correct order.

Accepted Answer

Step 1: Extract, Step 2: Cleanse, Step 3: Transform, Step 4: Load, Step 5: Verify. ETL begins with extraction, followed by cleaning, transformation, loading, and verification.

Answer

Step 1: Extract, Step 2: Transform, Step 3: Cleanse, Step 4: Load, Step 5: Verify

Answer

Step 1: Extract, Step 2: Load, Step 3: Transform, Step 4: Cleanse, Step 5: Verify

Answer

Step 1: Cleanse, Step 2: Extract, Step 3: Transform, Step 4: Load, Step 5: Verify

Question 10

During ETL, a data analyst discovers that a date column contains values like '01/02/2023' and '2023-01-02'. Which of the following is the best practice to ensure consistent date format before analysis?

Accepted Answer

Apply a standardized date parsing function to convert all dates. Applying a standardized date parsing function (e.g., `TO_DATE` in SQL or `pd.to_datetime` in Python) ensures all date values are converted to a single, consistent format regardless of the original representation. This is a fundamental ETL best practice to avoid ambiguity and enable accurate date-based filtering, aggregation, and joins during analysis.

Answer

Keep both formats and handle during analysis

Answer

Use regular expressions to parse and convert each format

Answer

Remove records with inconsistent date formats

Question 11

A data analyst finds that the "Age" column contains values like "N/A", "unknown", and negative numbers. Which data quality dimension is primarily affected?

Accepted Answer

Validity. Validity refers to the degree to which data conforms to defined business rules or constraints. Invalid entries (non-numeric, negative) violate the expected data type and range.

Answer

Accuracy

Answer

Consistency

Answer

Completeness

Question 12

A data team is creating a report for the board of directors. The board wants to see both the big picture and the ability to explore details for specific regions. Which TWO approaches should the team implement?

Accepted Answer

Include an interactive dashboard with filters by region.. Interactive dashboards with filters allow the board to see high-level summaries while drilling into region-specific details on demand. This approach aligns with modern BI tools like Tableau or Power BI, which support dynamic filtering and cross-filtering without requiring separate report pages.

Answer

Use a single summary metric for all regions.

Answer

Embed a table of data for each region in an appendix.

Answer

Provide a static executive summary with no drill-down.

Question 13

A data analyst is performing hypothesis testing to compare the mean sales of two store locations. Which TWO conditions must be satisfied to use a two‑sample t‑test? (Select TWO.)

Accepted Answer

The data is approximately normally distributed. The two-sample t-test assumes that the data in each group are approximately normally distributed. This is a key parametric assumption; if the sample sizes are large (typically n > 30), the Central Limit Theorem can relax this requirement, but for smaller samples, normality must hold to ensure valid test statistics and p-values.

Answer

The data is paired between the two locations

Answer

The sample sizes are equal

Answer

The variances of the two populations are equal

Question 14

A dashboard designer is building a sales performance dashboard for executives. According to dashboard design principles, which TWO practices should be applied? (Choose two.)

Accepted Answer

Use color coding consistently to group related metrics. Visual hierarchy emphasizes the most important metric, and clear labels ensure readability. Chartjunk should be minimized, not maximized.

Answer

Avoid titles and labels to keep the dashboard clean

Answer

Include excessive precision on all numbers to show accuracy

Answer

Maximize chartjunk to make the dashboard visually appealing

Question 15

A retail company's data analytics team needs to acquire point-of-sale (POS) transaction data from 200 stores daily. Each store sends a CSV file via email at the end of the day. The files often arrive late, have inconsistent column names (e.g., "StoreID", "Store_ID", "store_id"), and occasionally contain corrupted rows. The team manually processes these files, leading to frequent errors and delays. The company wants to automate the acquisition process to ensure data is available by 9 AM the next business day with high quality. Which approach best addresses these issues?

Accepted Answer

Create a script to automatically download email attachments, validate and standardize columns, and flag corrupted rows for review. It directly addresses all three issues: automating the retrieval of email attachments (handling late arrivals), standardizing inconsistent column names via a script (e.g., mapping 'StoreID', 'Store_ID', 'store_id' to a canonical schema), and implementing validation logic to flag corrupted rows for manual review. This approach ensures data is processed reliably by 9 AM without manual intervention, meeting the automation and quality requirements.

Answer

Hire a data entry contractor to manually check and re-enter data

Answer

Ask stores to use a standardized web form to enter data directly into a cloud database

Answer

Implement a VPN so stores can connect to the central database and write transactions in real time