P-value
The p-value is the smallest level of significance at which
we can still reject the null hypothesis, given the observed
sample statistic
When we are testing a
hypothesis, we always strive for
those ‘three zeros after the dot’.
This indicates that we reject the
null at all significance levels.
0.05 is often the ‘cut-off line’. If
our p-value is higher than 0.05
we would normally accept the
null
hypothesis (equivalent to
testing at 5% significance level).
If the
p-value is lower than 0.05 we
would reject the null.
Where and how are p-values used?
•
Most statistical software calculates p-values for each test
•
The researcher can decide the significance level post-factum
•
p-values are usually found with 3 digits after the dot (x.xxx)
•
The closer to 0.000 the p-value,
the better
Should you need to calculate a p-value ‘manually’, we suggest using
an online p-value
calculator, e.g.
this one.
