A data scientist is developing a model to predict patient readmission. The dataset is small (500 records) and imbalanced (10% readmitted). They split the data into 70% training and 30% test. After training, the model achieves 95% accuracy on training but 60% on test. Which combination of actions is most appropriate to improve evaluation reliability?

Increase the test set size to 50%.

Use a random split without stratification and rely on accuracy.

Use stratified splitting and consider cross-validation.

Train the model on the full dataset and evaluate on the same data.

What does a histogram show about a dataset?

The proportion of categories in a categorical variable

The change of a variable over time

The relationship between two numeric variables

The frequency distribution of a numeric variable across bins

Python InstitutePCAD - Certified Associate in Data Analytics with Python

Domain 4Objective 2

Statistical Methods and Machine Learning PCAD-31 Practice Questions (Page 6)

Part of the Data Analysis and Modeling domain, which accounts for 18.8% of the PCAD-31 exam. Python Institute does not publish an official question count, but from its 60-minute exam (~25–40 total, ~5–5 in this domain), expect 3–3 from this objective — we provide 30 practice questions to prepare you well beyond it. (estimate)

30questions here

6free pages

9concepts

18.8%of the exam

Questions 26–30

26application · easy
A data analyst has a numpy array `data` containing [10, 20, 30, 40, 100]. Which measure of central tendency is most robust to the outlier 100?
Select an answer first
27expert · hard
A data scientist is developing a model to predict patient readmission. The dataset is small (500 records) and imbalanced (10% readmitted). They split the data into 70% training and 30% test. After training, the model achieves 95% accuracy on training but 60% on test. Which combination of actions is most appropriate to improve evaluation reliability?
Select an answer first
28foundation · easy
What does a histogram show about a dataset?
Select an answer first
29application · easy
A regression model predicts house prices. The true values are [200, 300, 400] and the predicted values are [210, 290, 390]. What is the Mean Absolute Error (MAE)?
Select an answer first
30foundation · easy
Which pandas method returns a concise summary of central tendency, dispersion, and shape for all numeric columns in a DataFrame?
Select an answer first

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Statistical Methods and Machine Learning PCAD-31 Practice Questions (Page 6)

Questions 26–30

A data analyst has a numpy array `data` containing [10, 20, 30, 40, 100]. Which measure of central tendency is most robust to the outlier 100?

What does a histogram show about a dataset?

A regression model predicts house prices. The true values are [200, 300, 400] and the predicted values are [210, 290, 390]. What is the Mean Absolute Error (MAE)?

Which pandas method returns a concise summary of central tendency, dispersion, and shape for all numeric columns in a DataFrame?

Keep studying — Data Analysis and Modeling