Analyze Data

Determine data characteristics such as delay, feedback, and excitation level

Before you start estimating models from the selected data, you must check the data for any undesirable characteristics to determine the need to preprocess the data. You can do this by:

Plotting the data to examine both time-domain and frequency-domain behavior.
Using the advice command to analyze the data for the presence of constant offsets and trends, delay, possible feedback, and signal excitation levels.

Functions

`bode`	Bode frequency response of dynamic system
`bodemag`	Magnitude-only Bode plot of frequency response
`idplot`	Plot input and output channels of estimation data (Since R2023a)
`advice`	Analysis and recommendations for data or estimated linear models
`delayest`	Estimate time delay (dead time) from data
`isreal`	Determine whether model parameters or data values are real
`realdata`	Determine whether `iddata` is based on real-valued signals
`checkFeedback`	Identify possible feedback data (Since R2023a)
`pexcit`	Level of excitation of input signals
`impulseest`	Nonparametric impulse response estimation
`etfe`	Estimate empirical transfer functions and periodograms
`spa`	Estimate frequency response with fixed frequency resolution using spectral analysis
`spafdr`	Estimate frequency response and spectrum using spectral analysis with frequency-dependent resolution
`dataPlotOptions`	Option set for `idplot` when plotting input/output estimation data contained in a timetable, numeric matrices, or an `iddata` object (Since R2023a)

Topics

Is Your Data Ready for Modeling?
Before you start estimating models from data, you should check your data for the presence of any undesirable characteristics.
How to Plot Data in the App
After importing data into the System Identification app, as described in Represent Data, you can plot the data.
How to Plot Data at the Command Line
The following table summarizes the commands available for plotting time-domain, frequency-domain, and frequency-response data.
Identify Delay Using Transient-Response Plots
You can use transient-response plots to estimate the input delay, or dead time, of linear systems.
How to Analyze Data Using the advice Command
You can use the advice command to analyze time- or frequency- domain data before estimating a model.