Data Science Data Science-DATA Science 1

Question 1

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

Accepted Answer

Median

Answer

The median is the middle value of a sorted dataset and is unaffected by extreme values, making it the most robust measure of central tendency when outliers are present.

Question 2

What is the primary purpose of cross-validation in machine learning?

Accepted Answer

To assess how well a model generalizes to unseen data

Answer

Cross-validation partitions data into multiple folds and repeatedly trains/tests the model, giving a reliable estimate of how the model will perform on new, unseen data.

Question 3

In a neural network, what is the role of the activation function?

Accepted Answer

To introduce non-linearity into the model

Answer

Activation functions like ReLU or sigmoid introduce non-linearity, allowing neural networks to learn complex, non-linear relationships that a purely linear model could not capture.

Question 4

Which SQL clause is used to filter rows after a GROUP BY aggregation has been applied?

Accepted Answer

HAVING

Answer

HAVING filters groups produced by GROUP BY, whereas WHERE filters individual rows before aggregation occurs. HAVING is the correct clause for conditions on aggregated values.

Question 5

What does a confusion matrix's 'precision' metric measure?

Accepted Answer

The proportion of predicted positives that are truly positive

Answer

Precision = True Positives / (True Positives + False Positives). It measures how many of the model's positive predictions were actually correct, reflecting the cost of false alarms.

Data Science Practice Test

Data Science Practice Test

Data Science Data Science-DATA Science 1