Chapters 16 and 17 Flashcards
What does Statical Hypothesis Testing do?
It automates decision-making and favors objectivity by setting a threshold a priori.
a (alpha):
used to designate the significance threshold
What do you conclude and therefore do if a P value is less than the alpha?
Conclude that the difference is statistically significant and reject the null hypothesis
Type I Error
Incorrectly reject null
Type II Error
Incorrectly fail to reject null
Is there an option to accept null?
No, just to reject or not
Which type of error is preferred?
Usually, a type II error is preferred over type I error. e.g. prefer to release a criminal over imprisoning innocents
Choose alpha how?
a priori
Which alpha is common?
0.05 is common
Increasing alpha makes what more likely?
Increasing alpha makes type I more likely and type II less likely.
Decreasing alpha makes what more likely?
Decreasing alpha makes type II more likely and type I less likely
What kind of alpha will a very conservative scientist choose?
A low alpha, however, scientists often just report the exact P value and put less emphasis on choosing alpha.
You will never know…
from a single analysis if you have made a type I or type II error.
Even worse error than type I or type II.
Rejecting the null hypothesis correctly but wrong about effect direction.
The only way to reduce the chances of all three errors is…
to increase sample size.
