MCQs

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Overall MCQs for Reference

Which extension of ARIMA explicitly allows for the inclusion of explanatory variables?
a. ARCH
b. SARIMA
c. ARIMAX
d. VAR
Answer: c. ARIMAXgeeksforgeeks+1
In ARIMAX, what does the “X” stand for?
a. Extrapolation
b. Exogenous variables
c. Exploration
d. Exponent
Answer: b. Exogenous variablesmlpills+1
What type of variable is an exogenous regressor in ARIMAX?
a. A variable derived from the target series
b. A random noise component
c. An external variable not in the original time series
d. The error term
Answer: c. An external variable not in the original time seriesgeeksforgeeks+1
Which is the mathematical representation of ARIMAX?
a. Only lagged values of y
b. Adds lags of y and residuals only
c. Adds lags of y, residuals, and external predictors X
d. Only current values of X
Answer: c. Adds lags of y, residuals, and external predictors Xmlpills+1
In time series forecasting, why include exogenous variables?
a. They reduce the variance only
b. They can improve accuracy by explaining external effects
c. They are needed for data normalization
d. They eliminate seasonality
Answer: b. They can improve accuracy by explaining external effectstowardsdatascience+1
ARIMA models with additional regressors are most appropriate for which scenario?
a. Data with no trends
b. Data influenced by outside factors
c. Data with autocorrelation only
d. Data with only white noise
Answer: b. Data influenced by outside factorspeople.duke+1
Which of the following is NOT an example of an exogenous variable in forecasting sales?
a. Advertising spend
b. GDP index
c. Sales last year
d. National holidays
Answer: c. Sales last yeargeeksforgeeks+1
What is a prerequisite for explanatory variables used in ARIMAX?
a. Categorical only
b. Must be stationary themselves or made stationary
c. Only binary
d. No preprocessing needed
Answer: b. Must be stationary themselves or made stationarymlpills+1
ARIMA(p,d,q) models do NOT explicitly account for:
a. Seasonality
b. Trends
c. Exogenous variables
d. Noise
Answer: c. Exogenous variablesvskills+1
In Python’s statsmodels, which argument includes external regressors in SARIMAX?
a. exog
b. order
c. seasonal_order
d. trend
Answer: a. exoglinkedin+1
Why must exogenous variables be known for the forecast period in ARIMAX?
a. To estimate the error variance
b. So their effect can be forecasted as part of the model
c. To scale residuals
d. To backtest data only
Answer: b. So their effect can be forecasted as part of the modelgeeksforgeeks+1
Which process step comes AFTER incorporating exogenous variables into a time series model?
a. Model validation
b. Model clustering
c. Model reindexing
d. Data anonymization
Answer: a. Model validationmlpills+1
What is NOT a common diagnostic for ARIMAX models?
a. Residual analysis
b. Out-of-sample testing
c. Chi-square for independence
d. Model selection using AIC or BIC
Answer: c. Chi-square for independencereal-statistics+1
A time series’ response variable is sometimes called:
a. Endogenous variable
b. Independent variable
c. Instrumental variable
d. Causal factor
Answer: a. Endogenous variablepeople.duke+1
How does including exogenous variables affect model interpretability?
a. Makes the model interpretable as regression plus ARIMA
b. Makes the model uninterpretable
c. Removes statistical assumptions
d. Hides time-dependence
Answer: a. Makes the model interpretable as regression plus ARIMApeople.duke+1
Which form does an ARIMAX(1,1,1) model take?
a.
b.
c.
d.
Answer: b. geeksforgeeks+1
What does the parameter β represent in ARIMAX?
a. The effect of lagged y values
b. The effect of exogenous variable X
c. The regularization strength
d. The integration order
Answer: b. The effect of exogenous variable Xmlpills+1
Which is true about exogenous variables in ARIMAX?
a. They cannot be categorical
b. They must align in time with the dependent series
c. They only appear in moving average terms
d. They are always constant
Answer: b. They must align in time with the dependent seriesgeeksforgeeks+1
For what purpose might ARIMAX be preferred over plain ARIMA?
a. Data has no seasonality
b. Outliers are to be dropped
c. External variables influence the series
d. To reduce sample size
Answer: c. External variables influence the seriesmlpills+1
Which strategy is best when there are missing values in exogenous variables?
a. Delete those time steps
b. Fill with zeros unconditionally
c. Impute or forward-fill appropriately
d. Leave as-is
Answer: c. Impute or forward-fill appropriatelylinkedin+1
Which is NOT a benefit of using ARIMAX models?
a. Causal analysis
b. Enhanced forecasting
c. Only univariate usage
d. External factor impact
Answer: c. Only univariate usagegeeksforgeeks+1
If two exogenous variables are highly collinear, the effect in ARIMAX can be:
a. Improved accuracy
b. Biased coefficient estimates
c. Faster convergence
d. Lower forecast variance
Answer: b. Biased coefficient estimatesmlpills+1
The “integrated” (I) part of ARIMAX refers to:
a. The inclusion of exogenous variables
b. How many times data are differenced for stationarity
c. The maximum lag considered
d. Selection of feature variables
Answer: b. How many times data are differenced for stationarityvskills+1
Are ARIMAX and Regression with ARMA errors identical?
a. Yes
b. No, ARIMAX predicts y using X and past y
c. No, Regression with ARMA errors predicts y using X and ARMA error process
d. Both b and c
Answer: d. Both b and cpeople.duke+1
What is a common software for fitting ARIMAX models?
a. Excel with add-ons
b. Statsmodels and R
c. Tableau
d. Powerpoint
Answer: b. Statsmodels and Rlinkedin+1
Which AIC or BIC computation includes exogenous variable parameters?
a. Only for AR parameters
b. Only for X variables
c. For all included parameters
d. Not affected by exogenous regressors
Answer: c. For all included parametersreal-statistics+1
What does “forecasting with known future X values” mean in ARIMAX?
a. Using only past X values
b. Predicting y for periods where X values are known in advance
c. Using X’s mean value
d. Not possible in ARIMAX
Answer: b. Predicting y for periods where X values are known in advancegeeksforgeeks+1
Which is the main risk if an exogenous variable is actually endogenous?
a. Model underfitting
b. Causal inference may be invalid
c. Over-regularization
d. No impact
Answer: b. Causal inference may be invalidpeople.duke+1
In the ARIMAX model equation, the noise term is denoted as:
a. X
b. d
c.
d. β
Answer: c. mlpills+1
Which domain often uses ARIMAX for forecasting with explanatory variables?
a. Graphic design
b. Economic forecasting
c. Image recognition
d. Cryptography
Answer: b. Economic forecastinggeeksforgeeks+1
What is the requirement for time alignment of X and y in ARIMAX?
a. X must lag behind y
b. X and y must be for the same time points
c. X should always be one step ahead
d. No alignment needed
Answer: b. X and y must be for the same time pointsmlpills+1
What is an “exogenous shock” in ARIMAX modeling?
a. Random error in y
b. Sudden unexpected change in X affecting y
c. Parameter drift
d. Outlier removal
Answer: b. Sudden unexpected change in X affecting ypeople.duke+1
Which of the following can be an exogenous variable in ARIMAX?
a. Previous model errors
b. Calendar holidays
c. Residuals of y
d. Fitted values
Answer: b. Calendar holidaysgeeksforgeeks+1
What does parameter selection in ARIMAX involve?
a. Only lag selection for y
b. Only regressor selection for X
c. Both lag order and relevant exogenous variable inclusion
d. Outlier imputation
Answer: c. Both lag order and relevant exogenous variable inclusionmlpills+1
How is multicollinearity between exogenous variables detected?
a. High VIF (Variance Inflation Factor)
b. High AIC
c. Low forecast error
d. Increasing d parameter
Answer: a. High VIF (Variance Inflation Factor)geeksforgeeks+1
When is regular ARIMA preferable to ARIMAX?
a. Exogenous variables are unavailable or irrelevant
b. Forecasting with many predictors
c. Causal inference is needed
d. Forecasting long time periods ahead
Answer: a. Exogenous variables are unavailable or irrelevantmlpills+1
What does “white noise” mean in ARIMAX residuals?
a. Correlated error
b. Uncorrelated, zero-mean error
c. Increasing trend
d. Predicted values
Answer: b. Uncorrelated, zero-mean errorvskills+1
To prevent data leakage, exogenous variables for ARIMAX forecasting should:
a. Be from the entire dataset
b. Only use values available up to forecast time
c. Include test set values
d. Be interpolated
Answer: b. Only use values available up to forecast timelinkedin+1
Which of the following is true of ARIMAX coefficients for X variables?
a. Always positive
b. Can be positive or negative
c. Always between 0 and 1
d. Sum to 1
Answer: b. Can be positive or negativegeeksforgeeks+1
What does the inclusion of several exogenous variables in ARIMAX increase?
a. Model parsimony
b. Model complexity and degrees of freedom
c. Residual variance
d. Stationarity by default
Answer: b. Model complexity and degrees of freedommlpills+1
What is the main goal of differencing in ARIMAX?
a. Add seasonality
b. Achieve stationarity
c. Normalize data
d. Increase model complexity
Answer: b. Achieve stationaritygeeksforgeeks+1
ARIMAX is most beneficial over ARIMA when:
a. Regularity in data is absent
b. There are influential external factors
c. Only internal autocorrelation matters
d. There are no missing values
Answer: b. There are influential external factorsmlpills+1
When forecasting with ARIMAX, what must be provided for future time points?
a. Lag order p
b. Future values of exogenous variables X
c. Parameter β
d. Stationarity transformation
Answer: b. Future values of exogenous variables Xgeeksforgeeks+1
If a time series has trend and external shocks, which is more suitable?
a. ARIMA only
b. ARIMAX with appropriate X
c. Exponential Smoothing
d. Moving average
Answer: b. ARIMAX with appropriate Xmlpills+1
Which part of the ARIMAX equation can contain more than one parameter?
a. c only
b. AR, MA, and X regressors
c. β only
d. ε only
Answer: b. AR, MA, and X regressorsgeeksforgeeks+1
An example of a lagged exogenous variable would be:
a. X at current time t
b. X at previous time t-1
c. Differenced X
d. Mean of X
Answer: b. X at previous time t-1mlpills+1
If you do NOT include relevant exogenous variables in your model:
a. No effect
b. Omitted variable bias may occur
c. Lower test error
d. Increased stationarity
Answer: b. Omitted variable bias may occurpeople.duke+1
ARIMAX model is considered:
a. Only a regression model
b. Only a time series model
c. A hybrid of regression and time series
d. A clustering algorithm
Answer: c. A hybrid of regression and time seriesgeeksforgeeks+1
Which is necessary before using ARIMAX in machine learning for time series?
a. Data scaling and splitting
b. Variable selection and stationarity checks
c. Only data normalization
d. Only autocorrelation checks
Answer: b. Variable selection and stationarity checksmlpills+1
Which model is best if both seasonality and exogenous variables are present?
a. ARIMA
b. SARIMA
c. SARIMAX
d. AR model
Answer: c. SARIMAXtowardsdatascience+1

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