An analyst wants to show how the component pieces of a company's business units contribute to the company's overall revenue. Which of the following should the analyst use to best demonstrate this breakdown?
A. Box-and-whisker chart
B. Sankey diagram
C. Scatter plot matrix
D. Scatter plot matrix
Explanation
The question's key phrases are "component pieces" and "contribute to the company's overall revenue." This describes a part-to-whole relationship where the goal is to illustrate the breakdown of a total amount into its constituent segments.
A Sankey diagram is specifically designed for this purpose. It uses arrows or flows where the width of each flow is proportional to the quantity it represents (e.g., revenue amount).
How it works: In this scenario, one thick flow would represent the total company revenue on one side. This flow would then split into several smaller flows on the other side, each representing a different business unit. The width of each business unit's flow would immediately show its percentage contribution to the total.
Best Demonstration: It provides an intuitive, at-a-glance view of which business units are the largest and smallest contributors, making it "the best" tool for showing this specific type of breakdown.
Why the Other Options Are Not Correct
A. Box-and-whisker chart
Purpose: This chart is used to display the distribution of a dataset—its median, quartiles, and outliers. It is excellent for comparing statistical summaries across different categories (e.g., comparing the revenue distribution of five business units).
Why it's wrong: It does not show a part-to-whole relationship. A viewer cannot easily see from a box plot what percentage of the total company revenue comes from each unit. It shows how revenue is distributed within each unit, not how each unit contributes to the sum.
C. & D. Scatter Plot / Scatter Plot Matrix (Note: Option D is a duplicate in the question)
Purpose: A scatter plot is used to visualize the relationship or correlation between two variables (e.g., advertising spend vs. revenue generated for each business unit). A scatter plot matrix is a grid of scatter plots showing relationships between multiple variables.
Why it's wrong: Scatter plots are used for analyzing relationships and trends, not for breaking down a total into its components. They cannot effectively show how business units contribute to a total sum. Each point represents an observation, not a segment of a whole.
References
Data Visualization Principles:
Foundational texts on data visualization, such as Stephen Few's "Show Me the Numbers" or Cole Nussbaumer Knaflic's "Storytelling with Data," advocate for using chart types that match the specific communication goal. For a part-to-whole breakdown, they recommend charts like stacked bar charts, treemaps, or waterfall/Sankey diagrams for flows.
Nutanix Prism / Beam:
While Nutanix Prism uses a variety of visualizations, its focus on cost and resource allocation often leverages charts that show breakdowns and flows. Understanding which chart type is appropriate for a given analytical task is a core skill for any analyst working with the Nutanix platform's reporting capabilities. A Sankey diagram is the canonical choice for visualizing flow and contribution.
A data scientist uses a large data set to build multiple linear regression models to predict the likely market value of a real estate property. The selected new model has an RMSE of 995 on the holdout set and an adjusted R² of 0.75. The benchmark model has an RMSE of 1,000 on the holdout set. Which of the following is the best business statement regarding the new model?
A. The model should be deployed because it has a lower RMSE.
B. The model's adjusted R² is exceptionally strong for such a complex relationship.
C. The model fails to improve meaningfully on the benchmark model.
D. The model's adjusted R² is too low for the real estate industry.
Explanation:
The core of the question is about practical, business-relevant improvement, not just statistical improvement.
RMSE (Root Mean Square Error):
This metric represents the average magnitude of the model's prediction errors, in the same units as the target variable (in this case, dollars of market value).
Benchmark RMSE: $1,000
New Model RMSE: $995
The new model's error is only $5 less on average than the benchmark. For a real estate market where properties are worth hundreds of thousands or millions of dollars, an improvement of $5 is negligible and not meaningful from a business perspective. It does not justify the cost and risk of deploying a new, potentially more complex model.
Adjusted R² (Adjusted R-Squared):
This value of 0.75 indicates that the model explains 75% of the variance in the property values. While this is a reasonably good value, it is not "exceptionally strong" (eliminating option B) and its value is irrelevant if the model doesn't provide a better prediction than the existing benchmark.
The best business decision is to stick with the simpler, established benchmark model unless the new model demonstrates a substantial improvement in predictive accuracy, which it has not done.
Why the Other Options Are Not Correct
A. The model should be deployed because it has a lower RMSE.
Why it's wrong: This statement ignores the practical significance of the improvement. While the new model is technically statistically better (lower error), the improvement is so minuscule ($5) that it offers no real business value. Deploying a new model introduces complexity, maintenance, and potential for new errors, which is not worth the risk for such a trivial gain. A good data scientist must distinguish between statistical significance and business significance.
B. The model's adjusted R² is exceptionally strong for such a complex relationship.
Why it's wrong: An adjusted R² of 0.75 is good, but not exceptional. In many real-world scenarios, especially with large datasets, values of 0.8, 0.9, or higher are common for well-specified models. More importantly, this statement focuses on a secondary metric (goodness-of-fit) while completely ignoring the primary comparison to the benchmark, which shows no meaningful improvement. It's a distraction from the main conclusion.
D. The model's adjusted R² is too low for the real estate industry.
Why it's wrong:
There is no universal standard for a "good" R² value that applies to all industries. It is highly dependent on the specific market and data. A value of 0.75 is generally considered quite strong in many business analytics contexts, including real estate, where countless unpredictable factors (e.g., a buyer's emotional attachment) influence the final price. This value alone would not be a reason to dismiss the model; the reason for dismissal is its failure to beat the benchmark.
Valid References:
Model Evaluation Best Practices:
Standard machine learning texts (e.g., An Introduction to Statistical Learning by James, Witten, Hastie, and Tibshirani) emphasize that the choice between models should be based on their performance on a holdout set using metrics like RMSE. However, they also stress that the ultimate decision for deployment must consider the business context and the cost of error.
Nutanix Use Case (AI/ML Workloads):
On the Nutanix platform, a data scientist might use Nutanix Mine with Hadoop or run containerized ML workloads on Karbon. The principle of validating model performance against a business-relevant benchmark before deployment is a core tenet of the ML lifecycle (MLOps), which Nutanix solutions support. The platform provides the tools to run these comparisons, but the data scientist must still interpret the results correctly, as in this scenario.
A data scientist wants to evaluate the performance of various nonlinear models. Which of the following is best suited for this task?
A. AIC
B. Chi-squared test
C. MCC
D. ANOVA
Explanation:
AIC is the most appropriate metric for evaluating the performance of nonlinear models, especially when comparing multiple models. It balances model fit and complexity, helping to avoid overfitting. A lower AIC value indicates a better model, considering both how well the model fits the data and how many parameters it uses.
AIC is widely used for model selection in nonlinear regression, decision trees, and other complex models.
It is especially useful when comparing models that are not nested or when traditional metrics like R² are unreliable.
📚 References:
GeeksforGeeks – Evaluating Nonlinear Models
STHDA – Regression Model Accuracy Metrics
❌ Why Other Options Are Incorrect
B. Chi-squared test
Used for testing relationships between categorical variables, not for evaluating nonlinear model performance.
C. MCC (Matthews Correlation Coefficient)
Designed for binary classification tasks, not regression or general nonlinear model evaluation.
D. ANOVA (Analysis of Variance)
Suitable for comparing group means and linear models, but not ideal for complex nonlinear models.
📚 Reference:
FasterCapital – Nonlinear Regression Diagnostics
A data scientist built several models that perform about the same but vary in the number of features. Which of the following models should the data scientist recommend for production according to Occam's razor?
A. The model with the fewest features and highest performance
B. The model with the fewest features and the lowest performance
C. The model with the most features and the lowest performance
D. The model with the most features and the highest performance
Explanation:
Occam’s razor principle:
“The simplest explanation that still explains the data well is preferred.”
In ML, that means: if multiple models perform similarly, choose the simplest one (fewer parameters, fewer features, less complexity).
This helps with interpretability, scalability, and avoiding overfitting.
Option Analysis:
A. The model with the fewest features and highest performance ✅
Balances simplicity and performance.
Fewer features → easier to maintain, lower computation, less risk of overfitting.
This is exactly what Occam’s razor suggests.
B. The model with the fewest features and the lowest performance ❌
While simple, it sacrifices accuracy — not a good trade-off.
We want simplicity without degrading performance.
C. The model with the most features and the lowest performance ❌
Worst of both worlds: complex and poor performing.
Never recommended.
D. The model with the most features and the highest performance ❌
While performance is good, unnecessary complexity increases risk of overfitting, reduces interpretability, and makes deployment harder.
If another model performs similarly with fewer features, this violates Occam’s razor.
📝 Exam Tip:
Look for keywords:
“Occam’s razor” → simplest model that performs well.
“Production” → prefer maintainability, scalability, and interpretability in addition to accuracy.
📚 References:
CompTIA DataX (DY0-001) Objectives, Domain 3.0: Model Deployment and Lifecycle Management — select models for production considering complexity, performance, and scalability.
Murphy, K. (2012). Machine Learning: A Probabilistic Perspective.
Domingos, P. (2012). A Few Useful Things to Know About Machine Learning.
Which of the following image data augmentation techniques allows a data scientist to increase the size of a data set?
A. Clipping
B. Cropping
C. Masking
D. Scaling
Explanation:
The goal of data augmentation is to artificially expand the size and diversity of a training dataset without collecting new data. This is done by applying random-yet-realistic transformations to existing images.
How Cropping Increases Data Set Size:
When you apply random cropping to an image, you select a random portion of the original image (e.g., a 200x200 pixel section from a 250x250 image). This creates a new, unique image that is added to the training set. By performing this process multiple times on each original image, you can generate hundreds or thousands of new training examples from a single source image. This effectively "increases the size of the data set."
Why the Other Options Are Not Correct
A. Clipping
Purpose: In the context of image processing, clipping typically refers to restricting pixel values to a certain range (e.g., clipping values above 255 to 255 after a contrast adjustment) or clipping graphical elements that extend beyond a canvas boundary.
Why it's wrong: Clipping is an operation that constrains data; it does not create new data. It might be a step in a normalization process, but it does not generate new image files or variants that can be added to a dataset. Therefore, it does not increase the dataset size.
C. Masking
Purpose: Masking involves applying a binary mask to an image to isolate or hide specific regions. For example, you might mask out the background of a photo to focus on the main object.
Why it's wrong: While masking can be a useful pre-processing step to help a model focus on relevant features, it is not a primary data augmentation technique. Applying the same mask to an image does not create meaningfully new training examples in the way that geometric transformations do. It alters the image but doesn't typically generate multiple unique variants from a single source for the purpose of dataset expansion.
D. Scaling
Purpose: Scaling (or resizing) changes the dimensions of an image (e.g., from 500x500 pixels to 250x250 pixels).
Why it's misleading and not the best answer:
Scaling is a pre-processing requirement, not a standard data augmentation technique. Convolutional Neural Networks (CNNs) require all input images to be the same size. Therefore, you must scale all images to a fixed dimensions (e.g., 224x224) before feeding them into the model. While you could technically create different scaled versions, the standard practice is to scale everything to one consistent size. It is not used to create new training examples but to standardize existing ones. Cropping, flipping, and rotating are used for augmentation; scaling is used for pre-processing.
References
Deep Learning Frameworks:
The documentation for popular deep learning libraries like TensorFlow and PyTorch explicitly list RandomCrop as a core image augmentation transformation. For instance, torchvision.transforms.RandomCrop is designed to "Crop the given image at a random location" to increase data diversity.
Image Data Augmentation Standards:
Foundational textbooks and resources on computer vision (e.g., Deep Learning for Computer Vision by Rajalingappaa Shanmugamani) consistently list cropping, along with rotating, flipping, and color jittering, as fundamental techniques for dataset expansion. Scaling is universally listed as a pre-processing step, not an augmentation step.
A data scientist is building an inferential model with a single predictor variable. A scatter plot of the independent variable against the real-number dependent variable shows a strong relationship between them. The predictor variable is normally distributed with very few outliers. Which of the following algorithms is the best fit for this model, given the data scientist wants the model to be easily interpreted?
A. A logistic regression
B. An exponential regression
C. A linear regression
D. A probit regression
Explanation:
Step-by-step reasoning:
Scenario given:
Single predictor variable → simple regression candidate.
Scatter plot shows strong relationship → likely linear association.
Dependent variable is real-number (continuous) → regression (not classification).
Predictor is normally distributed with few outliers → assumption of linear regression satisfied.
Interpretability desired → linear regression is the most interpretable (slope, intercept).
Option Analysis:
A. Logistic regression ❌
Used when the dependent variable is categorical/binary (e.g., yes/no, spam/not spam).
Here, the dependent variable is continuous, so not appropriate.
B. Exponential regression ❌
Fits data that grows or decays exponentially.
Unless the scatterplot suggests exponential growth, this is not the best fit.
Also less interpretable than linear regression.
C. Linear regression ✅
Perfect fit: dependent is continuous, relationship is linear, predictor is normal with few outliers.
Very easy to interpret (slope = change in Y per unit change in X).
Matches the exam’s keywords: strong linear relationship + easy interpretation.
D. Probit regression ❌
Similar to logistic regression, but used for binary/categorical outcomes with a normal distribution assumption.
Not appropriate for continuous dependent variables.
📝 Exam Tip:
Continuous outcome → Linear regression (unless nonlinear patterns are present).
Binary outcome → Logistic or Probit regression.
Count data → Poisson regression.
Always match the dependent variable type to the regression method.
📚 References:
CompTIA DataX (DY0-001) Objectives, Domain 2.0: Exploratory Data Analysis and Statistics — select the appropriate statistical model based on variable types.
James, G., Witten, D., Hastie, T., & Tibshirani, R. (2013). An Introduction to Statistical Learning.
Penn State STAT 501: Simple Linear Regression
A data scientist is merging two tables. Table 1 contains employee IDs and roles. Table 2 contains employee IDs and team assignments. Which of the following is the best technique to combine these data sets?
A. inner join between Table 1 and Table 2
B. left join on Table 1 with Table 2
C. right join on Table 1 with Table 2
D. outer join between Table 1 and Table 2
Explanation:
An inner join is the best technique when you want to combine two tables based on matching values in a shared column—in this case, employee IDs. It returns only the rows where there is a match in both tables, ensuring that each employee has both a role and a team assignment.
Table 2: Employee ID + Team Assignment
Inner Join Result: Only employees who appear in both tables will be included.
This is ideal when the goal is to build a complete profile of employees who have both role and team data.
📚 References:
W3Schools – SQL INNER JOIN
Mode Analytics – SQL Joins Explained
❌ Why Other Options Are Incorrect
B. Left Join
Returns all rows from Table 1 and matches from Table 2. Includes employees with roles but no team assignment, which may introduce incomplete data.
C. Right Join
Returns all rows from Table 2 and matches from Table 1. Includes employees with team assignments but no role, which may also be incomplete.
D. Outer Join
Returns all rows from both tables, matched and unmatched. Useful for data audits, but not ideal when you only want complete records.
Which of the following distance metrics for KNN is best described as a straight line?
A. Radial
B. Euclidean
C. Cosine
D. Manhattan
Explanation:
In geometry, the shortest path between two points is a straight line. The Euclidean distance formula calculates the length of this straight-line segment in Euclidean space.
Formula:
For two points in a 2-dimensional space, p = (p1, p2) and q = (q1, q2), the Euclidean distance is calculated as:
d(p, q) = √( (q1 - p1)² + (q2 - p2)² )
This is a direct application of the Pythagorean theorem.
Visualization:
If you plot two points on a graph and draw a line directly between them, measuring the length of that line gives you the Euclidean distance. This holds true for higher dimensions as well (3D, 4D, etc.), even if we can't visualize it.
Why the Other Options Are Not Correct
A. Radial
Explanation: "Radial" is not a standard, standalone distance metric in machine learning or mathematics. The term is often used as an adjective. For example:
Radial Basis Function (RBF): A kernel used in SVMs that uses the Euclidean distance in its calculation.
Radial Distance: This can sometimes refer to the distance from a central point (origin) in a polar coordinate system.
Why it's wrong:It is not the specific name of a distance metric and does not describe a straight-line distance between two arbitrary points.
C. Cosine
Purpose: Cosine distance (derived from Cosine Similarity) measures the cosine of the angle between two vectors. It is a measure of orientation, not magnitude or direct distance.
Why it's wrong: It does not measure a straight-line path. Two vectors can be pointing in the same direction (cosine distance = 0) but be very far apart in terms of straight-line Euclidean distance. It is best used for comparing documents in text analysis where the magnitude (length of the document) is less important than the content direction.
D. Manhattan
Purpose: Also known as "city block" distance or L1 norm, it measures the distance between two points by summing the absolute differences of their coordinates.
Why it's wrong: It explicitly does not measure a straight line. Imagine being in a city with a grid-like street layout. The Manhattan distance is the total length of the path you would walk along the streets to get from point A to point B (e.g., 3 blocks North and 4 blocks East). The straight-line (Euclidean) distance would be the length of the diagonal you could walk through the buildings, which is shorter (√(3² + 4²) = 5 blocks).
Valid References:
Mathematics & Geometry:
Euclidean distance is a foundational concept in Euclidean geometry, named after the ancient Greek mathematician Euclid.
Machine Learning Textbooks:
Introductory texts like An Introduction to Statistical Learning (ISL) or Pattern Recognition and Machine Learning clearly define Euclidean distance as the straight-line distance between points in a feature space, especially in the context of K-Nearest Neighbors (KNN) and K-Means clustering algorithms.
In a modeling project, people evaluate phrases and provide reactions as the target variable for the model. Which of the following best describes what this model is doing?
A. Sentiment analysis
B. Named-entity recognition
C. TF-IDF vectorization
D. Part-of-speech tagging
Explanation
Sentiment analysis is the process of identifying and categorizing opinions or emotions expressed in text. In this scenario, where people evaluate phrases and provide reactions (positive, negative, neutral, etc.) as the target variable, the model is clearly designed to predict sentiment based on textual input.
It’s a supervised learning task where the model learns from labeled data (reactions).
Common in customer feedback, social media monitoring, and product reviews.
📚 References:
Stanford NLP – Sentiment Analysis
IBM – What is Sentiment Analysis?
❌ Why Other Options Are Incorrect
B. Named-entity recognition (NER)
Identifies proper nouns like names, locations, organizations—not emotions or reactions.
C. TF-IDF vectorization
A feature extraction method, not a modeling task. It converts text into numerical form for model input.
D. Part-of-speech tagging
Labels words as nouns, verbs, adjectives, etc.—used for grammatical analysis, not emotional interpretation.
📚 Reference:
spaCy – NLP Tasks Overview
Which of the following explains back propagation?
A. The passage of convolutions backward through a neural network to update weights and biases
B. The passage of accuracy backward through a neural network to update weights and biases
C. The passage of nodes backward through a neural network to update weights and biases
D. The passage of errors backward through a neural network to update weights and biases
Explanation:
What backpropagation is:
Backpropagation (“backward propagation of errors”) is the algorithm used to train neural networks.
It works by:
Forward pass
→ Input moves forward through the network to compute predictions.
Error calculation
→ Compare predictions to actual output using a loss function.
Backward pass
→ Compute the gradient of the error with respect to each weight (via chain rule / calculus).
Weight update
→ Adjust weights and biases to reduce error (using gradient descent).
Key concept: errors (not accuracy, not nodes, not convolutions) are propagated backward.
Option Analysis:
A. The passage of convolutions backward… ❌
Convolutions are specific to CNNs (convolutional neural networks).
Backpropagation applies to all neural networks, not just CNNs.
Wrong scope.
B. The passage of accuracy backward… ❌
Accuracy is a performance metric, not what gets propagated.
What actually propagates is the error/gradient.
C. The passage of nodes backward… ❌
Nodes (neurons) are structural parts of the network, not what propagates backward.
Incorrect.
D. The passage of errors backward… ✅
Correct definition: backpropagation = passing errors/gradients backward to adjust weights and biases.
📝 Exam Tip:
When you see “backpropagation”, always think:
Error → Gradient → Weight update.
Key phrase: “Backward propagation of errors.”
📚 References:
CompTIA DataX DY0-001 Exam Objectives, Domain 4.0: Machine Learning and AI Concepts — explain neural network training (forward pass, backpropagation).
Goodfellow, I., Bengio, Y., & Courville, A. (2016). Deep Learning.
Stanford CS231n: Backpropagation Notes
| Page 2 out of 11 Pages |