Practice Library
All MCQs
Browse exam-wise, subject-wise, and country-wise MCQs with explanations.
Choose an option to check your answer.
A.
Equal visual spacing may incorrectly imply equal time gaps
B.
The values become nonnumeric
C.
The line chart automatically sorts by size
D.
The sample variance becomes zero
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Correct Answer: A. Equal visual spacing may incorrectly imply equal time gaps
Explanation:
A time axis should reflect actual elapsed time, not merely record order.
Choose an option to check your answer.
A.
Only the series mean over time
B.
The hierarchy of cluster merges
C.
The distribution of category names
D.
Estimated autocorrelation across multiple lags
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Correct Answer: D. Estimated autocorrelation across multiple lags
Explanation:
An ACF plot displays temporal dependence at lag 1, lag 2, and beyond.
Choose an option to check your answer.
A.
Dividing every value by the first value
B.
Removing the first half of the series
C.
Subtracting the previous observation from the current observation
D.
Calculating a cumulative sum
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Correct Answer: C. Subtracting the previous observation from the current observation
Explanation:
The first difference is x_t minus x_{t-1}.
Choose an option to check your answer.
A.
Numeric and categorical variables
B.
Trend, seasonal, and remainder components
C.
Training and response labels only
D.
Means and p-values
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Correct Answer: B. Trend, seasonal, and remainder components
Explanation:
Decomposition represents a series as interpretable underlying components.
Choose an option to check your answer.
A.
The series becomes smoother but local changes are less visible
B.
The series becomes noisier and more detailed
C.
The sample size increases
D.
All seasonal patterns become exact
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Correct Answer: A. The series becomes smoother but local changes are less visible
Explanation:
Larger windows average over more periods and suppress more variation.
Choose an option to check your answer.
A.
To randomize the observation order
B.
To convert time into categories
C.
To calculate a survival probability
D.
To smooth short-term fluctuations and reveal underlying movement
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Correct Answer: D. To smooth short-term fluctuations and reveal underlying movement
Explanation:
A moving average replaces each point with a local average.
Choose an option to check your answer.
A.
Each observation with its sample mean
B.
Two unrelated category counts
C.
Each observation with the immediately previous observation
D.
The first and last variables only
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Correct Answer: C. Each observation with the immediately previous observation
Explanation:
A lag-1 plot places x at time t-1 against x at time t.
Choose an option to check your answer.
A.
Correlation between category labels
B.
Correlation between a series and lagged versions of itself
C.
The average of all observations
D.
A probability density estimate
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Correct Answer: B. Correlation between a series and lagged versions of itself
Explanation:
Autocorrelation measures temporal dependence at a chosen lag.
Choose an option to check your answer.
A.
A constant mean and variance with autocovariance depending only on lag
B.
A series with no observations
C.
A perfectly flat line
D.
A mean that grows every period
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Correct Answer: A. A constant mean and variance with autocovariance depending only on lag
Explanation:
Weak stationarity keeps first and second moments stable over time.
Choose an option to check your answer.
A.
It never lasts more than one period
B.
It contains no rises or falls
C.
It must repeat every seven days
D.
Its duration and timing are not fixed to a regular calendar period
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Correct Answer: D. Its duration and timing are not fixed to a regular calendar period
Explanation:
Cycles involve broad expansions and contractions with variable lengths.
Choose an option to check your answer.
A.
Any long-term increase
B.
A one-time structural break
C.
A pattern that repeats at a known and regular calendar frequency
D.
Uncorrelated random noise
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Correct Answer: C. A pattern that repeats at a known and regular calendar frequency
Explanation:
Seasonal behavior repeats over periods such as days, months, quarters, or years.
Choose an option to check your answer.
A.
A pattern repeating at a fixed seasonal period
B.
A long-term increase or decrease in the series level
C.
A single recording error
D.
A random permutation of values
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Correct Answer: B. A long-term increase or decrease in the series level
Explanation:
Trend reflects persistent movement over an extended interval.
