Before you can analyze any data, you need to understand how WinEEG organizes it. The software uses a dedicated database folder to store all patient information and EEG recordings. This structured approach is crucial for managing projects, especially when dealing with multiple subjects or sessions.

By default, this database resides in the WinEEG installation directory. Every new subject you add creates a specific subfolder within this database. This keeps all related files, from raw data to analysis results, neatly bundled together.

You can create a new subject by going to Database > New Subject. This action prompts you for patient details and creates the corresponding folder structure automatically. Keeping this organized from the start will save you a lot of headaches later.

With a subject folder ready, the next step is to import the raw EEG data. WinEEG natively works with Mitsar's own file format (.EEG). If you recorded data using Mitsar hardware, you can simply open these files directly within the correct subject's profile.

However, you'll often work with data from other systems. For this, WinEEG supports the European Data Format (.EDF or .EDF+), which is a standard for exchanging EEG and other physiological signals. To import an EDF file, select your subject, then navigate to File > Import > Data from EDF.

Once your data is loaded, you need to tell WinEEG how to display it. This is done by selecting a montage. A montage isn't just a list of electrodes; it's a specific configuration of how the electrical potential difference between electrodes is calculated and displayed. You're not looking at a single electrode's activity, but rather the difference between two points.

There are two key concepts here. The physical montage refers to how the electrodes were actually set up during recording, including the physical reference electrode(s). The referential montage is the mathematical reconstruction you apply in the software. This allows you to re-reference the data to different configurations without having to re-record anything.

WinEEG comes with many standard montages, which you can access via the Montage menu. These include common longitudinal and transverse bipolar setups, as well as various referential options.

The choice of reference is one of the most important decisions in EEG analysis. It can dramatically alter the appearance of your signals. Two of the most common referential montages are Linked Ears and the Average Reference montage.

You can switch between these on the fly in WinEEG to see how they affect your data. The Average Reference is often preferred for quantitative analysis (QEEG) because it provides a more distributed and balanced view of brain activity. However, if your data contains significant artifacts in a few channels, those noisy channels can distort the average and contaminate the entire dataset.

Finally, you'll need to adjust the display settings for optimal viewing. The amplitude scale, measured in microvolts per millimeter (uV/mm), controls the vertical size of the waveforms. The time scale, or sweep speed, controls how compressed or stretched the data appears horizontally. Finding the right balance is key to visually identifying important EEG patterns and artifacts.