Alpha level (:z-critical) aka cut-off: the likelihood of obtaining a type 1 error (errorenously rejecting Ho or random sampling error), traditional level is 0.05.
Directional: words like below or above or more or less are used.
Non-directional: words like difference or change or impact are used.
P score (:z-observed) aka observed score: Alpha is set by you like 0.05. P score is the probability of the observed score from your sample given that H0 (null hypothesis) is true.
"If your P score is less probable than alpha, you have a score to reject H0 (null hypothesis)".
Decision Errors
Type 1 error is false positive (errorneously rejecting H0) - the likelihood is alpha.
Type 2 error is false negative (errorneously failing to reject H0) - the likelihood is called beta. (Beta is not taught in this class)
As alpha decreases beta increases and visa versa.
Power: Probability that the test will lead to a reject H0 when H0 is actually false. You rejected H0 when you should reject H0.
Telescope example...type 2 error is a telescope that doesn't have enough power to see the asteriod that exists. If it has enough power, then you correctly reject H0.
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