When we make a prediction about the
outcome of an experimental situation it may
be one of two types.
• If we are very confident about the nature of
the outcome we might predict that our
manipulation of the independent variable will
cause a specific change in the dependent
variable, e.g. we may predict a positive change
(or we might be predicting a negative change).
This would be called a one tailed hypothesis
because we are only predicting one possible
outcome.