The alpha value is the probability
of making a Type
I Error. In a Hypothesis
Test a Type I error occurs when statistically
unlikely test results lead to the incorrect
conclusion that the null hypothesis should
be rejected. The alpha value is conventionally
designated by the symbol alpha (α ).
The alpha value is also called the 'level
of significance' and is selected based on
the importance of the test, a value of 0.05
would be common, with 0.01 for tests that
are critical, and even 0.001 in some cases.
A hypothesis test involves comparing the
with the previously agreed alpha value.
If the p-value is less than the alpha value
the alternative hypothesis will be accepted.