Stochastic is mainly used in combination with built in signal line and levels. Some prefer the levels some, on the other hand, signal
line. We could dispute which one is the better, but it probably mainly
depends on trading style.
Here is a version that, in some way, combines the two types.
signal lines idea is simple : when stochastic value is above central value
(stochastic being 50), then only the upper signal line is calculated, and the
lower signal line value is "inherited". When the value of stochastic is bellow
central value then the lower signal line is calculated and the upper
signal line is "inherited". That way we are getting a kind of
combination of levels and signal lines without a need to change the
value of the stochastic itself. As it is obvious it has its better sides
compared to both methods (especially avoiding some problems with
"trends" when signal lines alone are used). In any case extensive
testing is advised.