The Bipolar Scale is a specific type of rating scale characterised by a continuum between two opposite end points.
The bipolar scale has the advantage that it measures both the direction (side of the scale) and intensity (distance from the center) of the respondent's position on the concept of interest.
Some well-known bipolar scaling methods are referring to Semantic Differential (Osgood) scale and the Likert Scale(measuring either positive or negative response to a statement).
In some bipolar scales an even-point scale is used, where the middle option is not available. This is called a "forced choice" method, since the neutral option is removed. The neutral option can be seen as an easy option to take when a respondent is unsure, and so whether it is a true neutral option is questionable.