EVENT COUNTING
⌘8 This operation counts the number of 'events'
in the selected block that satisfy two Boolean criteria: greater than
one user-selected value, and less than a second user-selected value.
An 'event' occurs when the data cross one of the two Boolean 'boundaries'.
A 'negative' event is counted when the data drop below the lower
limit, and a 'positive' event is counted when the data rise above
the upper limit. The default minimum
and maximum values are the mean of the lower and upper limits of the
data range in the block, which includes 100% of the data and results in
a single event in each category. An example of event counting is shown below.
You can set new limits in three ways:
- When the 'minimum' or 'maximum' buttons are clicked,
the limits are reset to these values
- When the 'greater than' or 'less than' buttons are clicked,
you can use the mouse to move cursor in the block window to graphically
select the upper and lower limits.
- Finally, you can directly type in the limit values in the edit fields
(hitting "return" will force the program to recalculate the results).
- You can include all the events, or elect to analyze only events longer than a minimum duration. Toggle these options with the 'count all events' button.
The right side of the window shows basic statistics for the durations of positive and negative events (mean, SD, range), and a histogram of these values. Only complete events (including both beginnings and endings) are shown here. You can elect to analyze only events longer than a minimum duration. The 'show all events' button forces the basic event counters to show all events, not just those longer than the minimum duration.
The 'save details' button makes a text file (Excel format) containing the polarity (positive or negative), start time, duration, and basic statistics (mean, SD, minimum, maximum) for each identified event. Some additional considerations include:
- You cannot send results to disk or printer by hitting the 'p' key,
as usual. Instead, use the 'print' button (this button
only appears if output has been selected from the FILE
menu)
- This option DOES NOT print to a tabular file (the output format is
incompatible).
Additional considerations for EVENT COUNTING:
- The 'distribution' button produces a histogram (bar graph) of frequency distribution in a small moveable window. If the file has more than one channel, you can click on buttons for different channels and get those means (you can also use the keyboard to select channels). With an option in the PREFERENCES menu, you can have different histogram windows for each channel, or use the same small window for all channels.
- You cannot send results to disk or printer by hitting the 'p' key, as usual. Instead, use the 'print' button (this button only appears if output has been selected from the Output Menu).
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