Data Science MCQ Flashcards
7 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 7 Data Science MCQ flashcards as text
What is multicollinearity in a regression model?
Answer: High correlation among predictor variables
Multicollinearity occurs when independent variables are highly correlated with each other.
Which activation function outputs values between 0 and 1 and is often used for binary classification output?
Answer: Sigmoid
The sigmoid function squashes inputs into the (0, 1) range, suitable for probabilities.
What does the bias-variance tradeoff describe?
Answer: The balance between underfitting and overfitting error sources
Lowering bias often raises variance and vice versa, so models must balance both.
Which SQL clause is used to filter groups after aggregation?
Answer: HAVING
HAVING filters aggregated results, whereas WHERE filters individual rows before grouping.
What is the purpose of a train-validation-test split?
Answer: To tune hyperparameters and get an unbiased final performance estimate
The validation set tunes hyperparameters while the held-out test set gives an unbiased estimate.
Which method imputes missing numerical values using neighboring observations?
Answer: K-nearest neighbors imputation
KNN imputation fills missing values using the values of the most similar records.
In time series analysis, what does 'stationarity' mean?
Answer: Statistical properties like mean and variance stay constant over time
A stationary series has constant mean, variance, and autocorrelation structure over time.