probability and significance Flashcards
probability
a measure of the likelihood that a particular event will occur
0 indicates statistical impossibility
1 indicates statistical certainty
significance
a statistical term that tells us how sure we are that a difference or correlation exists.
a ‘significant’ result means that the researcher can reject the null hypothesis.
critical value
when testing a hypothesis, the numerical boundary or cut-off point between acceptance and rejection of the null hypothesis.
null hypothesis
the null hypothesis states that there is ‘no difference’ between the conditions
alternative hypothesis
directional or non-directional hypothesis
usual level of significance in psychology
- 05 or 5%
0. 01 or 1% in research with high human cost, e.g. drug trails, or research that can never be replicated
type I error
false positive.
when null hypothesis rejected and alternative hypothesis accepted, when null hypothesis should have been accepted.
researcher claims to have found a significant difference or correlation when one does not exist.
type II error
false negative.
when the null hypothesis is accepted and alternative hypothesis is rejected, when the alternative hypothesis should have been accepted.
one-tailed test
directional hypothesis
two-tailed test
non-directional hypothesis
