Research & Data Analysis Flashcards

A Likert-scale survey question (1–5) measuring satisfaction is best analyzed with which statistical approach?

Answer: Mann-Whitney U test as a non-parametric alternative

Ordinal Likert data often violates normality assumptions, making the Mann-Whitney U test a robust non-parametric choice for group comparisons.

In a multiple regression model, the variance inflation factor (VIF) is used to detect:

Answer: Multicollinearity among predictors

VIF quantifies how much a predictor's variance is inflated due to linear correlations with other predictors in the model.

Which sampling method ensures proportional representation of subgroups within the population?

Answer: Stratified random sampling

Stratified random sampling divides the population into strata and samples from each proportionally, guaranteeing subgroup representation.

A receiver operating characteristic (ROC) curve plots sensitivity against:

Answer: 1 – Specificity (false positive rate)

The ROC curve plots the true positive rate (sensitivity) on the y-axis against the false positive rate (1 – specificity) on the x-axis across all classification thresholds.

In Bayesian inference, the posterior distribution is proportional to:

Answer: The product of the prior and the likelihood

Bayes' theorem states posterior ∝ likelihood × prior; the marginal likelihood acts as a normalizing constant.

A researcher finds r = 0.92 between two variables but the relationship is explained entirely by a third variable. This is called:

Answer: Spurious correlation

A spurious correlation appears strong but disappears when a confounding variable is controlled, revealing no true direct relationship.

When building a predictive model, overfitting is best identified by:

Answer: High training accuracy and low test accuracy

Overfitting occurs when a model memorizes training data, yielding high in-sample performance but poor generalization to unseen test data.