Data Science Time Series Analysis

Question 1

In time series analysis, a series is considered stationary if:

Accepted Answer

Its mean, variance, and autocovariance are constant over time

Answer

It has no seasonal patterns whatsoever

Answer

Its values are always positive

Answer

Its values always increase over time

Question 2

What does the Autocorrelation Function (ACF) measure in a time series?

Accepted Answer

The correlation between a time series and a lagged version of itself

Answer

The correlation between two completely different time series

Answer

The variance of the time series at each individual time point

Answer

The trend direction of the time series over the full period

Question 3

What does the 'I' stand for in the ARIMA model?

Accepted Answer

Integrated

Answer

Independent

Answer

Interaction

Answer

Interval

Question 4

What is seasonality in a time series?

Accepted Answer

Regular, periodic patterns that repeat at fixed time intervals

Answer

Long-term upward or downward movement in the data

Answer

Random fluctuations with no predictable pattern

Answer

A sudden structural change in the mean level of the series

Question 5

The Partial Autocorrelation Function (PACF) is primarily used to determine:

Accepted Answer

The order of the Autoregressive (AR) component

Answer

The order of the Moving Average (MA) component

Answer

Whether the series is stationary or needs differencing

Answer

The optimal forecasting horizon for the model

Question 6

What is white noise in time series analysis?

Accepted Answer

A series of uncorrelated random variables with constant mean and variance

Answer

A sequence with a consistent upward trend over time

Answer

Data with strong and predictable seasonal patterns

Answer

A series that requires differencing to become stationary

Question 7

What does 'trend' represent in a time series?

Accepted Answer

The long-term increase or decrease in the data over an extended period

Answer

Periodic fluctuations that repeat on a yearly basis

Answer

Random variation around the series mean value

Answer

The moving average calculated across the entire series