# Data Preprocessing

## Apps

Econometric Modeler | Analyze and model econometric time series |

## Classes

`LagOp` | Create lag operator polynomial |

## Functions

## Examples and How To

**Prepare Time Series Data for Econometric Modeler App**Prepare time series data at the MATLAB

^{®}command line, and then import the set into Econometric Modeler.**Import Time Series Data into Econometric Modeler App**Import time series data from the MATLAB Workspace or a MAT-file into Econometric Modeler.

**Plot Time Series Data Using Econometric Modeler App**Interactively plot univariate and multivariate time series data, then interpret and interact with the plots.

**Transform Time Series Using Econometric Modeler App**Transform time series data interactively.

**Nonseasonal Differencing**Take a nonseasonal difference of a time series.

**Nonseasonal and Seasonal Differencing**Apply both nonseasonal and seasonal differencing using lag operator polynomial objects.

**Moving Average Trend Estimation**Estimate long-term trend using a symmetric moving average function.

**Seasonal Adjustment Using a Stable Seasonal Filter**Deseasonalize a time series using a stable seasonal filter.

**Seasonal Adjustment Using S(n,m) Seasonal Filters**Apply seasonal filters to deseasonalize a time series.

**Parametric Trend Estimation**Estimate nonseasonal and seasonal trend components using parametric models.

**Use Hodrick-Prescott Filter to Reproduce Original Result**Use the Hodrick-Prescott filter to decompose a time series.

**Compare One-Sided and Two-Sided Hodrick-Prescott Filter Results**Smooth the U.S. GDP by applying the one-sided and two-sided Hodrick-Prescott filters, and compare the resulting smoothed trends.

**Specify Lag Operator Polynomials**Create lag operator polynomial objects.

## Concepts

**Econometric Modeling**Understand model-selection techniques and Econometrics Toolbox™ features.

**Stochastic Process Characteristics**Understand the definition, forms, and properties of stochastic processes.

**Analyze Time Series Data Using Econometric Modeler**Interactively visualize and analyze univariate or multivariate time series data.

**Data Transformations**Determine which data transformations are appropriate for your problem.

**Trend-Stationary vs. Difference-Stationary Processes**Determine the characteristics of nonstationary processes.

**Time Series Decomposition**Learn about splitting time series into deterministic trend, seasonal, and irregular components.

**Moving Average Filter**Some time series are decomposable into various trend components. To estimate a trend component without making parametric assumptions, you can consider using a filter.

**Seasonal Filters**You can use a seasonal filter (moving average) to estimate the seasonal component of a time series.

**Seasonal Adjustment**Seasonal adjustment is the process of removing a nuisance periodic component. The result of a seasonal adjustment is a deseasonalized time series.

**Time Base Partitions for ARIMA Model Estimation**When you fit a time series model to data, lagged terms in the model require initialization, usually with observations at the beginning of the sample.