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Question 1

Which measure of central tendency is most resistant to the influence of outliers in a dataset?

Accepted Answer

Median

Answer

The median is the middle value when data is sorted and is unaffected by extreme values, making it robust to outliers. The mean, by contrast, shifts significantly when outliers are present.

Question 2

In the context of machine learning, what is the primary purpose of a validation set?

Accepted Answer

To tune hyperparameters and select the best model configuration

Answer

A validation set is used during development to tune hyperparameters and compare different model configurations. The test set (not the validation set) is reserved for final unbiased evaluation.

Question 3

Which probability distribution is commonly used to model the number of events occurring within a fixed time interval when events happen independently?

Accepted Answer

Poisson distribution

Answer

The Poisson distribution models the count of independent events in a fixed interval of time or space, given a known average rate. It is widely used for event-count data such as customer arrivals or server requests per minute.

Question 4

What is the purpose of the 'learning rate' hyperparameter in gradient descent optimization?

Accepted Answer

It controls how much the model's weights are updated at each step

Answer

The learning rate scales the gradient update applied to the model's weights at each iteration. A rate too high causes divergence, while a rate too low leads to very slow convergence.

Question 5

Which of the following best describes the concept of 'feature engineering'?

Accepted Answer

Transforming or creating input variables to improve model performance

Answer

Feature engineering involves creating new input variables or transforming existing ones — such as encoding categoricals, scaling numerics, or combining columns — to provide the model with more informative signals.

Data Science Practice Test

Data Science Practice Test

Data Science Data Science-FREE Data Science 1