Loading/browsing data

You can load and browse data in ANSLAB, using 'viewing' as analysis type. Depending on the data format you have chosen, you are prompted to choose the channels you wish to load (ACQ, VEE, VPD, EDF, VIV and TXT) or the variables you wish to import (MAT). This procedure will be described for each data format separately below.

Raw files

First you specify how many channels you wish to load:

You are then asked to set a display sample rate, which loaded data will be resampled to before display. Lower samplerates are faster for drawing, but, in turn, less accurate. For many channels, such as respiration, pulse or eda, a sample rate of 50 Hz is more than sufficient. Other data types, like ecg or emg, need higher temporal resolution (400 and 1000 Hz respectively).

Then, ANSLAB reads in header information of the file and lets you choose the channels to load from a list of channel labels found in the file. For Vivologic files, the channel labels are fixed and comprise only those traces that are hardcoded in the viv-file. All other calculated traces are not available to ANSLAB.

For each channel you are also asked to choose whether the data type is digital (marker type) or analogue (any physiological data channel). This is important as finding specific values in a signal is much faster for digital channels, than for analog signal. Moreover, a different type of resampling is used for marker type channels to avoid filter ripple. Generally, if you are loading a psychophysiological data signal, select 'no', for any other channel choose 'yes'.

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ANSLAB files (ans)

This data format is used by ANSLAB to store segmented data as a vector of 'trials', or to store averaged signal (across trials or subjects). If you are loading a 'Cell'-type file that contains multiple trials, you can only load one file at a time and jump from trial to trial using the segment navigation buttons.

If you are loading averaged data segments, you can load a theoretically unlimited number of files and display them together. To do this, load files to a data 'slot', as set with the modifyied file edit box on the ANSLAB menu window:

Files are then plotted together and labelled on a legend according to their file names.

When the 'ANS'-file format is selected, switching to 'Event'-data mode will allow you to load corresponding statistical ANS-files related to the 'raw' signals. To this end, the 'open data file(s)'-button is changed to 'open stats file(s)' as shown below:

You can load an arbitrary number of stats files. You should make sure however, that f-values and t-values are not mixed, as this will disrupt proper scaling. Stats-files are produced when running statistical tests (t-tests or ANOVAs) from the 'Calculate'-menu.

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MATLAB data files (MAT)

All standard analysis results in ANSLAB are stored in standard MATLAB mat-files in the corrsponding folder for the analysis type. You can then reimport these variables to have a look at your analysis results. After choosing a mat-file, ANSLAB reads its entire content, and asks you which variables to load for displaying:

You can import up to 4 RAW-type variables and 4 EVENT-type variables, that will be accessible in ANSLAB at the chosen data slot. Activate the corresponding data slot and select the variable name from the adjacent dropdown-box.

For RAW-signals you additionally have to make sure that the sampling rate is correct to get correct timing information. EVENT-type variables do not require a sampling rate, but a separate time vector, as they are, by definition, non-uniformly sampled variables. This timing variable is included in mat-files written by ANSLAB and must be selected from the 'timing variable'-dropdownbox.

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