AIRLINE_LLF - Log Likelihood Function of an Airline Model

Returns an array of cells for the initial/quick guess of the model's parameters

Syntax

AIRLINE_LLF(X, Order, mean, sigma, s, theta, theta2)
X
is the univariate time series data (a one-dimensional array of cells (e.g., rows or columns)).
Order
is the time order in the data series (i.e., the first data point's corresponding date (earliest date=1 (default), latest date=0)).
Order Description
1 ascending (the first data point corresponds to the earliest date) (default)
0 descending (the first data point corresponds to the latest date)
mean
is the model mean (i.e., mu).
sigma
is the standard deviation of the model's residuals/innovations.
s
is the length of seasonality (expressed in terms of lags, where s > 1).
theta
is the coefficient of first-lagged innovation (see model description).
theta2
is the coefficient of s-lagged innovation (see model description).
Warning

AIRLINE_LLF() function is deprecated as of version 1.63: use AIRLINE_GOF function instead.

Remarks

  1. The underlying model is described here.
  2. The time series is homogeneous or equally spaced.
  3. The time series may include missing values (e.g., #N/A) at either end.
  4. AIRLINE_GUESS returns the model's parameters in the following order:
    1. $\mu$
    2. $\theta$
    3. $\Theta$
    4. $\sigma$
  5. The AIRLINE_GUESS sets the $\mu$ and $\sigma$ equal to the differenced sample (i.e., $Z_t=(1-L)(1-L^s)Y_t$) average and standard deviation respectively, and it sets the $\theta = 0$ and $\Theta=0$

Examples

Example 1:

 
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A B C D
Date Data    
1/1/2008 -0.300 AIRLINE  
1/2/2008 -1.278 Mean 0.0481
1/3/2008 0.244 theta(1) 0.14
1/4/2008 1.276 theta(2) 0.30
1/6/2008 1.733 Sigma 2.74127
1/7/2008 -2.184 s 2
1/8/2008 -0.234    
1/9/2008 1.095    
1/10/2008 -1.087    
1/11/2008 -0.690    
1/12/2008 -1.690    
1/13/2008 -1.847    
1/14/2008 -0.978    
1/15/2008 -0.774    

Formula Description (Result)  
=AIRLINE_AIC(Sheet1!$B$2:$B$15,1,$D$3,$D$6,$D$7,$D$4,$D$5) 65.6 Akaike's information criterion (AIC)
=AIRLINE_LLF(Sheet1!$B$2:$B$15,1,$D$3,$D$6,$D$7,$D$4,$D$5) -25.47 Log-Likelihood Function
=AIRLINE_CHECK($D$3,$D$6,$D$7,$D$4,$D$5) 1 Is the AIRLINE model stable?

 

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References

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