DA0-001 Practice Test 22 — 15 Questions

Question 1

Refer to the exhibit. What is the most likely issue causing the unexpectedly low count?

Accepted Answer

The signup_date column is in a different date format. Option A is correct because if the signup_date column is stored in a different date format (e.g., MM/DD/YYYY), the comparison with '2023-01-01' (YYYY-MM-DD) may not match many records. Option B is wrong because GROUP BY is not needed for COUNT(*). Option C is wrong because database refresh does not directly affect query result. Option D is wrong because indexing affects performance, not correctness.

Answer

The customers table is indexed incorrectly

Answer

The query is missing a GROUP BY clause

Answer

The database was not refreshed

Question 2

A data team is using web scraping to collect competitor pricing data. The target website has anti-scraping measures like CAPTCHAs and rate limiting. Which approach is most effective?

Accepted Answer

Use rotating proxies and respectful delays. Option D is correct because using rotating proxies and respectful delays mimics human behavior and avoids detection. Option A is wrong because increasing request frequency triggers rate limiting. Option B is wrong because using a single IP address is easily blocked. Option C is wrong because disregarding robots.txt may violate terms and lead to legal issues or IP bans.

Answer

Use a single IP address

Answer

Disregard robots.txt

Answer

Increase request frequency

Question 3

A healthcare organization collects patient questionnaire data via paper forms at clinics. The forms are scanned and sent to a central office, where staff manually enter data into an electronic system. This process is slow and error-prone. The organization wants to reduce manual entry errors and speed up data availability. Which method should they adopt?

Accepted Answer

Use optical character recognition (OCR) to digitize the forms and automatically populate the database. Optical Character Recognition (OCR) can convert scanned images to text automatically, reducing manual entry errors and speeding up the process. Requiring patients to fill out online forms may not be feasible for all patients, especially those without internet access. Continuing manual entry with double-checking is still slow and labor-intensive. Sending to an external company introduces additional cost and potential privacy concerns.

Answer

Continue manual entry but double-check all entries

Answer

Send forms to an external data processing company

Answer

Require patients to fill out forms online at home

Question 4

A data analyst is performing data acquisition from multiple source files. Which TWO data profiling tasks should the analyst complete before loading the data into the target system?

Accepted Answer

Verify data types and formats. Identifying missing values and verifying data types are fundamental data profiling tasks that help ensure data quality before acquisition. Building models, creating dashboards, or clustering are not part of profiling.

Answer

Create a dashboard for stakeholders

Answer

Build a linear regression model

Answer

Perform cluster analysis

Question 5

A company needs to visualize the trend of monthly sales revenue over the past two years. Which chart type is most appropriate?

Accepted Answer

Line chart. Option B is correct because line charts are best for showing trends over time. Option A (pie) is for parts of a whole; Option C (scatter) is for relationships between variables; Option D (bar) compares categories but not trends as clearly.

Answer

Bar chart

Answer

Scatter plot

Answer

Pie chart

Question 6

A data analyst creates a dashboard showing average order value by region. The chart indicates that one region has an unusually high average. Investigation reveals that the region has very few orders, but one large purchase inflates the average. Which data transformation should the analyst apply to improve the visualization?

Accepted Answer

Use median instead of mean for aggregation. Option A is correct because using an appropriate aggregation like median or grouping with sufficient data can mitigate the impact of outliers. Other options do not address the root cause.

Answer

Apply logarithmic scaling to the y-axis

Answer

Change the chart type to a pie chart

Answer

Remove all outliers from the dataset

Question 7

A data analyst needs to visualize sales per capita across U.S. states. States with small populations but high sales (e.g., Delaware) appear too prominent on a choropleth map. Which technique best addresses this issue?

Accepted Answer

Use a choropleth map with rates instead of raw sales. Option D is correct because a choropleth map adjusted for per-capita values properly normalizes by population. Other options either do not normalize or distort the data.

Answer

Switch to a bar chart sorted by sales

Answer

Use a bubble chart with size proportional to sales

Answer

Apply a log scale to the color gradient

Question 8

A marketing team wants to compare the growth rates of four product categories over the last quarter. Which chart type would best display this?

Accepted Answer

Bar chart. Option C is correct because a bar chart comparing growth percentages across categories is clear and straightforward. Other options are less effective for comparing discrete metrics.

Answer

Pie chart

Answer

Stacked bar chart

Answer

Line chart

Question 9

A scatter plot of advertising spend vs. revenue shows no clear correlation, but the analyst suspects a relationship exists. Which addition to the plot could help reveal a hidden trend?

Accepted Answer

Add a trendline. Option A is correct because adding a trendline (e.g., linear regression) can reveal patterns in noisy data. Other options may obscure or not address the issue.

Answer

Change to a bar chart

Answer

Increase the marker size

Answer

Remove data points with low spend

Question 10

A data scientist has a dataset with 50 variables and wants to identify clusters of similar observations. Which visualization technique is most suitable for reducing dimensionality to 2D while preserving cluster structure?

Accepted Answer

Scatter plot of first two principal components. Option C is correct because PCA (or t-SNE) is designed for dimensionality reduction to visualize clusters. Other options are less effective for high-dimensional data.

Answer

Heatmap of correlations

Answer

Scatter matrix (pairplot)

Answer

Parallel coordinates plot

Question 11

A dashboard needs to show sales trends for each of five regions over the past year. The intended audience wants to compare trends easily. Which chart type is best?

Accepted Answer

Line chart with multiple lines. Option B is correct because multiple line chart lines allow comparison of trends across regions. A stacked bar would show composition, not trends.

Answer

Pie chart

Answer

Stacked bar chart

Answer

Area chart

Question 12

An executive dashboard must display high-level KPIs such as current revenue, profit margin, and customer count. Which visualization type is most appropriate for each KPI?

Accepted Answer

KPI card showing value and variance. Option D is correct because KPI cards (or tiles) display a single metric clearly and concisely. Other options are less effective for immediate understanding.

Answer

Pie chart

Answer

Sparkline for each KPI

Answer

Gauge chart

Question 13

A dataset contains salaries ranging from $25,000 to $2,500,000, with most salaries under $100,000. Which chart type best shows the distribution without distortion from extreme values?

Accepted Answer

Box plot. Option B is correct because box plots display distribution with outliers clearly separated, unaffected by extreme values in terms of scale. Histograms may compress the bulk of data.

Answer

Scatter plot

Answer

Histogram with equal bin widths

Answer

Line chart

Question 14

Which TWO are best practices for designing effective dashboards? (Select exactly two.)

Accepted Answer

Use a single page to avoid scrolling.. Options A and C are correct. A single-page dashboard provides an at-a-glance view, and consistent color schemes improve readability. 3D charts (B) can distort perception; including every metric (D) clutters; pie charts (E) are often misused.

Answer

Use 3D charts for visual appeal.

Answer

Use pie charts for comparing parts of a whole.

Answer

Include every possible metric to provide completeness.

Question 15

Which THREE actions improve the accessibility of data visualizations for users with visual impairments? (Select exactly three.)

Accepted Answer

Provide text alternatives for charts (e.g., data tables).. Options B, C, and D are correct. Clear labels help all users; text alternatives allow screen readers; sufficient contrast improves readability. Using only color (A) excludes colorblind users; animation (E) can be distracting and not accessible.

Answer

Use only color to convey information.

Answer

Add animated transitions between views.

DA0-001 Practice Test 22 — 15 Questions

Exhibit

DA0-001 Practice Test 22 — 15 Questions

Exhibit