Time Series Analysis Study Guide 2026

Everything you need to pass the Time Series Analysis exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.

📋 Time Series Analysis Exam Format at a Glance

60
Questions
90 min
Time Limit
70.00%
Passing Score

📚 Time Series Analysis Topics to Study (23)

✍️ Sample Time Series Analysis Questions & Answers

1. Why can multiplicative error ETS models produce prediction intervals that are asymmetric?
Because multiplicative errors scale with the level, creating non-constant forecast variance

When errors are multiplicative, the forecast variance grows with the forecast level, producing wider intervals at higher levels and narrower ones at lower levels.

2. What is 'cointegration' in the context of multiple non-stationary time series?
Two non-stationary series share a long-run equilibrium relationship

Cointegrated series are individually I(1) but their linear combination is stationary, implying a stable long-run relationship.

3. What are 'impulse response functions' (IRFs) in VAR analysis?
Functions showing how each variable responds over time to a shock in one variable

IRFs trace the dynamic effect of a one-unit shock to one variable on itself and all other variables in the system over subsequent time periods.

4. What happens to the prediction interval width in exponential smoothing as the forecast horizon increases?
It generally widens, reflecting growing uncertainty further into the future

Forecast uncertainty accumulates over time, so prediction intervals fan out as the horizon increases, reflecting greater uncertainty at longer lead times.

5. What is the ETS framework in time series modeling?
Error, Trend, Seasonality — a unified state-space framework for exponential smoothing

ETS provides a state-space formulation of exponential smoothing, enabling model selection via AIC and proper prediction interval computation.

6. In practice, what number of differences (d) is rarely needed for most economic and financial time series?
d > 2

Most real-world series become stationary after one or two differences; d > 2 is a sign of over-differencing.

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