Lesson 3: Inferential Statistics Flashcards
Null Hypothesis
The opposite of the hypothesis proposed; usually states that there is NO difference, relationship, or effect
Alternative Hypothesis
The proposed hypothesis or idea, typically that there IS a difference, relationship, or effect
Alpha
The probability of INCORRECTLY REJECTING the null (saying there is a difference when there is not)
Type 1 Error
False Alarm; Detecting a difference when there is not one
Beta
Probability of incorrectly failing to reject the null (saying there is not a difference when there is)
Type II Error
Missing It – Failing to detect a difference when there is one
Power**
Ability of a test to detect a difference when a difference exists (get it right)
Power Analysis
A method for determining how large a sample size must be to detect a difference if in fact a difference exists
Most statistical analysis use an alpha level of..
0.05
P-Value
the probability that the observed statistic occurred by chance
-Since researchers get to choose their own, it represents their tolerance that their findings are wrong (due to chance)
How do we draw a conclusion looking at our statistics?
We compare our p-value to alpha. If P value is LESS than alpha, it is unlikely that the difference occurred by statistical chance.
What do smaller p-values indicate?
That the observed statistic was less likely to have happened by chance. It does NOT mean that the results have greater significance or a larger detected difference.
What happens when alpha is set to 0.05?
You incorrectly find a significant different 5% of the time
What happens when the alpha level is changed from 0.05 to 0.01?
The probability of a Type I error decreases.
In a study of effectiveness of Medication X for treating hypertension, the null hypothesis could be..
Taking Medication X does not change patients’ blood pressure.
