Data Patterns

Question 1

To which concept is this equation applied?

Answer 1

Compute Lag k autocorrelation coefficient (r_k) between observations, Y_t and Y_t-k that are k periods apart.

Question 2

Within this autocorrelation coefficient equation, to what does the following refer?

Y_t-k

Answer 2

The observation at k time periods earlier than t.

Also, time period t-k.

Question 3

Within this autocorrelation coefficient equation, to what does the following refer?

Y_t

Answer 3

The observation time period

Question 4

Within this autocorrelation coefficient equation, to what does the following refer?

Ӯ

Answer 4

The mean of the value of the series

Question 5

Within this standard error/standard deviation of autocorrelation coefficient equation, to what does the following refer?

k

Answer 5

The time lag.

Question 6

Within this standard error/standard deviation of autocorrelation coefficient equation, to what does the following refer?

r_i

Answer 6

The autocorrelation at time lag i.

Question 7

Within this autocorrelation coefficient equation, to what does the following refer?

r_k

Answer 7

The autocorrelation coefficient for a lag of k periods.

Examples:

r₁ = Calculation of the lag 1 correlation coefficient;
Correlation between Y_t and Y_t-1

r₂ = Calculation of the lag 2 correlation coefficient;
Correlation between Y_t and Y_t-1

r_k = Calculation of the lag k correlation coefficient;
Correlation between Y_t and Y_t-1

Question 8

Generally, as the number of time lags (k) increases/decreases, the magnitude of the autocorrelation coefficients increase/decrease.

Answer 8

Generally, as the number of time lags (k) increases, the magnitude of the autocorrelation coefficients decrease.

Question 9

To which concept is this equation applied?

Answer 9

This equation is used to compute the standard deviations (or standard errors) of the autocorrelation coefficients.

Question 10

True or False

The irregular component is the part of a time series that remains after the other components have been removed.

Answer 10

True.

{Extra info about the irregular component goes here}

Question 11

True or False

The seasonal component is a pattern of change that repeats itself year after year.

Answer 11

True.

{Extra info about the seasonal component goes here}

Question 12

True or False

The cyclical component is the wavelike fluctuation around the trend.

Answer 12

True.

{Extra info about the cyclical component goes here}