Data Science FREE Data Science Analysis Question and Answers 2

Question 1

Which technique is most appropriate for reducing the dimensionality of a dataset while preserving the maximum variance?

Accepted Answer

Principal Component Analysis (PCA)

Answer

PCA projects data onto orthogonal components that capture the most variance, making it the standard technique for dimensionality reduction.

Question 2

In exploratory data analysis, what does a right-skewed distribution indicate about the data?

Accepted Answer

The tail extends toward higher values with most data concentrated on the left

Answer

A right-skewed distribution has a longer tail on the right side, meaning most observations cluster at lower values while fewer extreme high values pull the tail rightward.

Question 3

When performing A/B testing, what is the primary purpose of calculating statistical power before running the experiment?

Accepted Answer

To determine the minimum sample size needed to detect a meaningful effect

Answer

Statistical power analysis before an experiment determines the sample size required to reliably detect an effect of a given size at a specified significance level.

Question 4

Which metric is most appropriate for evaluating a classification model when the dataset has a severe class imbalance (e.g., 95% negative, 5% positive)?

Accepted Answer

Area Under the Precision-Recall Curve (AUPRC)

Answer

AUPRC focuses on the performance of the minority class and is more informative than accuracy when class distribution is highly imbalanced.

Question 5

What is the main risk of using too many features relative to the number of observations in a regression model?

Accepted Answer

Overfitting, where the model captures noise rather than the true signal

Answer

When features outnumber observations, the model can perfectly fit training data including its noise, leading to poor generalization on new data.

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Data Science Practice Test

Data Science FREE Data Science Analysis Question and Answers 2