Behavioral Research: Statistical Methods
CG3.402Vinoo Alluri•Monsoon 2025-26•4 credits
Mock Paper 1 — All Units Mix
Duration: 120 min • Max marks: 100
Section A — MCQ (20 × 1 = 20)
20 marks- 1.Reaction time of 400 ms is twice as fast as 800 ms. The statement is valid because RT is on which scale? (a) Nominal (b) Ordinal (c) Interval (d) Ratio1 m
- 2.Correct frequentist interpretation of a 95% CI: (a) 95% probability the parameter lies in this interval (b) 95% of data lie in this interval (c) If we repeated the procedure many times, 95% of such intervals would contain the parameter (d) The parameter is in this interval 95% of the time1 m
- 3.A researcher reports p = 0.03. Which statement is correct? (a) P(H₀ true) = 3% (b) Assuming H₀ true, 3% chance of data this extreme or more (c) 3% chance the finding is a fluke (d) 97% chance H₁ is true1 m
- 4.Three independent groups, normality severely violated. Test? (a) One-way ANOVA (b) Repeated-measures ANOVA (c) Kruskal-Wallis (d) Friedman1 m
- 5.CLT says: (a) Any large sample is Normal (b) Sampling distribution of sample mean approaches Normal as n grows (c) Population must be Normal (d) Outliers cancel in large samples1 m
- 6.Mauchly's test of sphericity is relevant for: (a) Chi-square (b) Repeated-measures ANOVA (c) Independent t-test (d) Pearson r1 m
- 7.A scale consistently reads 5 kg above true weight: (a) Reliable but not valid (b) Valid but not reliable (c) Both (d) Neither1 m
- 8.Bonferroni with m = 10 tests at family-wise α = 0.05 sets each test's α to: (a) 0.05 (b) 0.005 (c) 0.5 (d) 1 − 0.95¹⁰1 m
- 9.R command for P(≤ 6 heads in 10 fair flips): (a) dbinom(6,10,0.5) (b) pbinom(6,10,0.5) (c) qbinom (d) rbinom1 m
- 10.Bayesian posterior is proportional to: (a) prior × evidence (b) prior × likelihood (c) likelihood ÷ prior (d) evidence ÷ prior1 m
- 11.Pearson r = 0 between two variables. The correct conclusion: (a) They are independent (b) No linear association; nonlinear possible (c) Identical means (d) One causes the other inversely1 m
- 12.In a 2×3 contingency table, df for χ² independence test: (a) 5 (b) 6 (c) 2 (d) 11 m
- 13.Tiny effect, p < 0.001, n = 50,000. Conclude: (a) Very important effect (b) Real but practically meaningless (c) p-value wrong (d) H₀ definitely false1 m
- 14.NOT a measure of central tendency: (a) Mean (b) Median (c) Standard deviation (d) Mode1 m
- 15.Regression with R² = 0.4 means: (a) 40% predictions correct (b) Correlation is 0.4 (c) 40% of variance in Y explained by model (d) Slope is 0.41 m
- 16.Sphericity violation in RM-ANOVA is corrected by: (a) Welch (b) Greenhouse-Geisser (c) Bonferroni (d) Tukey HSD1 m
- 17.Bayes Factor BF₁₀ = 8 indicates: (a) Strong for H₀ (b) Anecdotal for H₁ (c) Moderate for H₁ (d) No evidence1 m
- 18.Best sampling method to ensure rare subgroups are represented: (a) Simple random (b) Convenience (c) Stratified (d) Snowball1 m
- 19.A scree plot is used in: (a) Hypothesis testing (b) Factor analysis / PCA to choose # factors (c) χ² tests (d) Regression diagnostics1 m
- 20.Failing to reject H₀ when H₀ is false: (a) Type I (b) Type II (c) Sampling (d) Measurement1 m
Section B — MSQ (10 × 2 = 20)
20 marks- 1.Valid forms of reliability: (a) Test-retest (b) Construct (c) Inter-rater (d) Parallel forms (e) Ecological2 m
- 2.A ratio scale supports: (a) Ordering (b) Add/subtract (c) Multiply/divide (d) Meaningful mean (e) All of the above2 m
- 3.Threats to internal validity: (a) History (b) Selection bias (c) Practice / testing effects (d) Sampling from one university (e) Experimenter bias2 m
- 4.True of the t-distribution: (a) Heavier tails than Normal (b) Used when σ unknown (c) Shape depends on df (d) Symmetric around 0 (e) Approaches Normal as df → ∞2 m
- 5.Correct about p-hacking: (a) Optional stopping inflates Type I (b) Trying many analyses and reporting favorable one is p-hacking (c) Pre-registration helps (d) Reporting only the most interesting of many outcomes is fine (e) Selectively dropping participants until p < .05 is p-hacking2 m
- 6.Assumptions of OLS regression: (a) Linearity (b) Independence of errors (c) Homoscedasticity (d) Predictors must be normal (e) Normality of residuals2 m
- 7.Inflate family-wise Type I error: (a) Many independent t-tests on same data (b) Pre-specifying one hypothesis (c) Testing 50 outcomes (d) Many subgroup analyses (e) Bonferroni correction2 m
- 8.Correct Bayes-rule term mappings: (a) P(H) is prior (b) P(D|H) is posterior (c) P(D|H) is likelihood (d) P(H|D) is posterior (e) P(D) is the marginal probability of the data2 m
- 9.Non-parametric tests: (a) Mann-Whitney U (b) Independent t-test (c) Kruskal-Wallis (d) Friedman (e) One-way ANOVA2 m
- 10.Increase statistical power: (a) ↑ sample size (b) ↑ α from .01 to .05 (c) Within-subjects design (d) Reduce measurement noise (e) ↓ true effect size2 m
Section C — Short descriptive (6 × 5 = 30)
30 marks- 1.A university shows overall bias against admitting women, but every individual department admits women at higher rates than men. Explain how this is possible.5 m
- 2.Distinguish reliability and validity. Can a measurement be valid without being reliable? Concrete example.5 m
- 3.Diagnostic test has 95% sensitivity and 5% false-positive rate. Disease prevalence is 2%. A patient tests positive. Compute P(disease | positive). Comment.5 m
- 4.Differentiate FWER and FDR. When use each? Which is more conservative?5 m
- 5.PCA vs Factor Analysis — conceptual differences and when to use each.5 m
- 6.A researcher claims that ice-cream sales correlate with drownings in a city. Critically evaluate.5 m
Section D — Long descriptive (3 × 10 = 30)
30 marks- 1.A psychologist tests whether a new mindfulness app reduces anxiety. 60 students, randomly assigned 30 to app and 30 to waitlist; anxiety measured pre and 8 weeks later. (i) IV and DV with scales. (ii) Hypotheses. (iii) Recommend a test with justification. (iv) Assumptions. (v) Additional analyses.10 m
- 2.Multiple regression: Income = β₀ + β₁·Education + β₂·Experience + β₃·Age + ε, n = 200. R² = 0.42, adjR² = 0.41, F(3,196) = 47.3, p < .001. β₁ = 4500 (SE 800, p<.001); β₂ = 1200 (SE 400, p<.01); β₃ = 50 (SE 150, p = .74). VIFs 9.8 / 11.3 / 12.1. (i) Interpret R² and adjR². (ii) Interpret each β. (iii) Why is Age non-significant? (iv) What problem do VIFs reveal and what to do?10 m
- 3.Define statistical power. List five factors affecting it. A study finds p = 0.18 with n = 30/group and claims 'no effect of the treatment'. Critically evaluate and explain how Bayesian analysis helps.10 m
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