Exploratory Data Analysis Flashcards
7 cards from real MS-DS Master of Data science practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Exploratory Data Analysis flashcards as text
Which statistical measure is MOST resistant to the influence of outliers when describing the center of a distribution?
Answer: Median
The median is not affected by extreme values because it depends only on the middle rank, not the magnitude of any values.
A violin plot combines which two visualization types?
Answer: Box plot and kernel density estimate
A violin plot overlays a kernel density estimate on each side of a box plot, showing both distributional shape and summary statistics.
When performing EDA on a dataset with 50 features, which technique best identifies groups of highly correlated predictors?
Answer: Clustered heatmap of the correlation matrix
A clustered heatmap reorders features by hierarchical clustering so correlated blocks appear together, making multicollinearity visible at scale.
What does a right-skewed (positively skewed) distribution indicate about the relationship between mean and median?
Answer: Mean is greater than median
In a right-skewed distribution, the long tail on the right pulls the mean upward beyond the median.
In the context of EDA, what is the primary purpose of a quantile-quantile (Q-Q) plot?
Answer: Assessing whether data follows a theoretical distribution
A Q-Q plot plots sample quantiles against theoretical quantiles; points falling on the diagonal line indicate the data matches that distribution.
Which transformation is most appropriate to stabilize variance in a right-skewed continuous variable with all positive values?
Answer: Log transformation
The log transformation compresses large values and stretches small ones, reducing right skew and stabilizing variance for positive data.
A dataset contains a categorical variable with 200 unique levels. Which EDA approach is MOST practical for summarizing its distribution?
Answer: Bar chart of the top 10 levels plus an 'Other' category
Grouping rare categories into 'Other' reduces visual clutter while preserving the most meaningful frequency information.