*seasonal* is an easy-to-use and full-featured R-interface to
X-13ARIMA-SEATS, the newest seasonal adjustment software developed by
the United States Census Bureau.

*seasonal* depends on the x13binary package to access
pre-built binaries of X-13ARIMA-SEATS on all platforms and does not
require any manual installation. To install both packages:

`install.packages("seasonal")`

`seas`

is the core function of the *seasonal*
package. By default, `seas`

calls the automatic procedures of
X-13ARIMA-SEATS to perform a seasonal adjustment that works well in most
circumstances:

`m <- seas(AirPassengers)`

For a more detailed introduction, check our article in the *Journal
of Statistical Software* or consider the vignette:

`vignette("seas")`

In *seasonal*, it is possible to use almost the complete
syntax of X-13ARIMA-SEATS. The X-13ARIMA-SEATS syntax uses
*specs* and *arguments*, with each spec optionally
containing some arguments. These spec-argument combinations can be added
to `seas`

by separating the spec and the argument by a dot
(`.`

). For example, in order to set the ‘variables’ argument
of the ‘regression’ spec equal to `td`

and
`ao1999.jan`

, the input to `seas`

looks like
this:

`m <- seas(AirPassengers, regression.variables = c("td", "ao1955.jan"))`

The best way to learn about the relationship between the syntax of
X-13ARIMA-SEATS and *seasonal* is to study the comprehensive list of
examples. Detailed information on the options can be found in the
Census Bureaus’ official manual.

*seasonal* has a flexible mechanism to read data from
X-13ARIMA-SEATS. With the `series`

function, it is possible
to import almost all output that can be generated by X-13ARIMA-SEATS.
For example, the following command returns the forecasts of the ARIMA
model as a `"ts"`

time series:

```
m <- seas(AirPassengers)
series(m, "forecast.forecasts")
```

There are several graphical tools to analyze a `seas`

model. The main plot function draws the seasonally adjusted and
unadjusted series, as well as the outliers:

```
m <- seas(AirPassengers, regression.aictest = c("td", "easter"))
plot(m)
```

The `view`

function is a graphical tool for choosing a
seasonal adjustment model, using the seasonalview
package, with the same structure as the demo website of seasonal.
To install seasonalview,
type:

`install.packages("seasonalview")`

The goal of `view`

is to summarize all relevant options,
plots and statistics that should be usually considered.
`view`

uses a `"seas"`

object as its main
argument:

`view(m)`

*seasonal* is free and open source, licensed under GPL-3. It
requires the X-13ARIMA-SEATS software by the U.S. Census Bureau, which
is open source and freely available under the terms of its own license.

To cite seasonal in publications use:

Sax C, Eddelbuettel D (2018). “Seasonal Adjustment by X-13ARIMA-SEATS
in R.” *Journal of Statistical Software*, *87*(11), 1-17.
doi: 10.18637/jss.v087.i11 (URL:
https://doi.org/10.18637/jss.v087.i11).

Please report bugs and suggestions on GitHub. Thank you!