An LSR alert will fire if the most-recent $spread price is outside the boundary created by multiplying the standard deviation of the price series with the supplied "standard deviation multiplier", and then adding or subtracting the least squares regression value at the same point in time.
The Spread Analyzer provides the customers with the ability to create 3 of these alert for each spread.
Written by Michael Bigger. Follow me on Twitter and StockTwits.