Correlogram - ACF
Modeling for Forecast Forecast Data The Base Model Linear Trend Logistic Growth Others Models Look for a best approximation of the truth Forecasting Skill
Tools for Identifying a Best Model Review
Scatterplot and Correlation Coefficient - Review Y X
Correlogram as Model Identifier Timeplot Correlogram Models That Work
Autocorrelation Coefficient Definition: The correlation coefficient between Y t and Y (t-k) is called the autocorrelation coefficient at lag k and is denoted as k. By definition, 0 = 1. Autocorrelation of a Random Series: If the series is random, k = 0 for k = 1,...
Process Correlogram Lag, k kk 1
Sample Autocorrelation Coefficient Sample Autocorrelation at lag k.
Standard Error of the Sample Autocorrelation Coefficient Standard Error of the sample autocorrelation if the Series is Random.
Z- Test of H 0 : k = 0 Reject H 0 if Z 1.96
Test of Randomness Correlogram
Box-Ljung Q Statistic Definition
Sampling Distribution of Q BL (m) | H 0 H 0 : 1 = 2 =… k = 0 Q BL (m) | H 0 follows a 2 (DF=m) distribution Reject H 0 if Q BL > 2 (95%tile)