FREE Data Science Analysis Question and Answers Flashcards
6 cards from real 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 6 FREE Data Science Analysis Question and Answers flashcards as text
Which technique is most appropriate for reducing the dimensionality of a dataset while preserving the maximum variance?
Answer: Principal Component Analysis (PCA)
PCA projects data onto orthogonal components that capture the most variance, making it the standard technique for dimensionality reduction.
In exploratory data analysis, what does a right-skewed distribution indicate about the data?
Answer: The tail extends toward higher values with most data concentrated on the left
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.
When performing A/B testing, what is the primary purpose of calculating statistical power before running the experiment?
Answer: To determine the minimum sample size needed to detect a meaningful effect
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.
Which metric is most appropriate for evaluating a classification model when the dataset has a severe class imbalance (e.g., 95% negative, 5% positive)?
Answer: Area Under the Precision-Recall Curve (AUPRC)
AUPRC focuses on the performance of the minority class and is more informative than accuracy when class distribution is highly imbalanced.
What is the main risk of using too many features relative to the number of observations in a regression model?
Answer: Overfitting, where the model captures noise rather than the true signal
When features outnumber observations, the model can perfectly fit training data including its noise, leading to poor generalization on new data.
In time series analysis, what does the Augmented Dickey-Fuller (ADF) test assess?
Answer: Whether the series is stationary or contains a unit root
The ADF test checks for the presence of a unit root in a time series, where rejecting the null hypothesis indicates the series is stationary.