![]() ![]() This is the Series A data from Box and Jenkins, a set of 197 concentration values from a chemical process taken at two hour intervals. Open Chemical Process Concentration – Series A.xlsx ( Sheet 1 tab). ![]() ![]() Chemical Process Concentration - Series A We will also examine how differencing results in stationarity with the ACF and PACF plots. Later, ACF on model residuals are used to assist in determining how well a model fits the autocorrelation structure, ideally with the residuals showing no statistically significant We will use the ACF and PACF to get a general idea of what models should be used, but let the automatic algorithms do the heavy lifting of determining which model is optimal. PACF denotes the Partial AutoCorrelation Function We will use the lag utility and scatterplots to demonstrate this for 3 lags using the Series A data.ĪCF denotes the AutoCorrelation Function plot (sometimes called aĬorrelogram). If the slope is positive, the autocorrelation is positive if there is a negative slope, the autocorrelation is negative. the same data at lag □ may show a positive or negative trend. Just as correlation measures the extent of a linear relationship between two variables, autocorrelation measures the linear relationship between lagged values of data.Ī plot of the data vs. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |