I fit a simple linear model $y = bX$ to a data set today, and that produced 24 residuals (I have 24 data points, one for each year from 1984-2007). I would like to test the time-independence of the residuals of my model, and I was recommended by my supervisor to use the Ljung-Box test. The
Box.test function in R takes 4 arguments:
x: a numeric vector or univariate time series.
lag: the statistic will be based on lag autocorrelation coefficients.
type: test to be performed: partial matching is used.
fitdf: number of degrees of freedom to be subtracted if x is a series of residuals.
lag mean, and what value would you guys recommend I use for the test? Also, what does
fitdf represent, and what would the value for that parameter be in my case? Finally, the value of
x is a vector of my 24 residuals, correct?