Data Science Statistical Concepts and Analysis Questions 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 Data Science Statistical Concepts and Analysis Questions and Answers flashcards as text
A data scientist observes that two variables have a Pearson correlation coefficient of -0.92. What does this indicate?
Answer: A strong negative linear relationship
A Pearson correlation of -0.92 indicates a strong negative linear relationship, meaning as one variable increases, the other decreases proportionally.
Which assumption is NOT required for a valid ordinary least squares (OLS) linear regression?
Answer: Normal distribution of independent variables
OLS regression requires normality of residuals, not normality of the independent variables themselves.
In a hypothesis test, a p-value of 0.03 with a significance level of 0.05 leads to which conclusion?
Answer: Reject the null hypothesis
Since the p-value (0.03) is less than the significance level (0.05), we reject the null hypothesis.
What is the primary purpose of cross-validation in predictive modeling?
Answer: To estimate how well a model generalizes to unseen data
Cross-validation estimates a model's generalization performance by repeatedly training and testing on different subsets of the data.
A dataset has a mean of 50, a median of 42, and a mode of 38. What type of skewness does this distribution exhibit?
Answer: Positive skew
When the mean is greater than the median, which is greater than the mode, the distribution is positively (right) skewed.
Which metric is most appropriate for evaluating a classification model when the dataset has a 95:5 class imbalance?
Answer: F1 Score
The F1 Score balances precision and recall, making it far more informative than accuracy when classes are heavily imbalanced.