MS-DS Master of Data science Exploratory Data Analysis 4

Question 1

During EDA you discover that a numeric feature has a bimodal distribution. What does this most likely suggest?

Accepted Answer

There may be two distinct subpopulations in the data

Answer

Two peaks in a distribution often indicate the presence of two underlying groups or processes that were combined in the dataset.

Question 2

Which dimensionality reduction technique is commonly used in EDA to project high-dimensional data onto 2D for visual cluster discovery?

Accepted Answer

t-SNE

Answer

t-SNE (t-distributed Stochastic Neighbor Embedding) is designed to preserve local neighborhood structure, making clusters visible in 2D projections.

Question 3

When examining a scatter plot of two variables, you observe a curved (non-linear) pattern rather than a straight line. Which correlation measure is MORE appropriate than Pearson's r?

Accepted Answer

Spearman's rank correlation

Answer

Spearman's correlation measures monotonic association using ranks rather than raw values, handling non-linear but monotonic relationships better than Pearson's r.

Question 4

A feature has the values: [1, 2, 3, 4, 100]. The z-score of 100 is approximately 2.18. Should 100 be flagged as an outlier using the z-score method with threshold |z| > 3?

Accepted Answer

No, because its z-score does not exceed 3

Answer

The z-score method only flags values with |z| > 3 as outliers; z ≈ 2.18 is below that threshold, so 100 would not be flagged by this rule alone.

Question 5

Which EDA technique is specifically designed to reveal how the marginal distribution of one variable changes across levels of a second categorical variable?

Accepted Answer

Box plots grouped by category

Answer

Side-by-side box plots, one per category level, directly compare the center, spread, and skew of the numeric variable across groups.

MS-DS Master of Data science Practice Test

MS-DS Master of Data science Practice Test

MS-DS Master of Data science Exploratory Data Analysis 4