Total world rice production (million tonnes)

First discuss the assumption of independence and the possibility of serial correlation of the errors.

The Durbin-Watson statistic is:

High serial correlation ==> d close to zero.

Is d = 1.291 indicative of serial correlation?

Select Random Normal Data. Click Accumulate, then click Simulate about 100 times to build up the sampling distribution of d.

A value as low as 1.291 is very unlikely for data from a normal linear model.

Strong evidence that years with unusually high (or low) yield tend to follow each other.

Warning

An unusually small Durbin-Watson statistic can be caused by either serial correlation or nonlinearity.


The time series gives the total world rice production (million tonnes) between 1961 and 2001.