Hard to believe these are typos #9
Description
This is from the documentation of ARCH package
"The null hypothesis of the Augmented Dickey-Fuller is that there is a unit root, with the alternative that there is no unit root. If the p-value is above a critical size, then the null cannot be rejected that there and the series appears to be a unit root."
on p. 152 a p-value of 0.997 is reported (in a figure which references KPSS test while the table shown clearly says that it is an ADF test) and the following conclusion is made "Given the p-value of 0.997, we can reject our null hypothesis of the unit root, and we conclude that our process is weakly stationary."
In a couple of pages "Please note that we need to set trend="t" here so that the model includes a constant.
If not, we would get a spurious regression." In the statsmodels' ARIMA class documentation, it is stated clearly that trend is "Parameter controlling the deterministic trend. Can be specified as a string where ‘c’ indicates a constant term, ‘t’ indicates a linear trend in time, and ‘ct’ includes both."
It's quite doubtful that the author of this book understands what he is writing about. But at least he could have checked the documentation of the packages used in it.