The 365 Data Science team is proud to invite you to our own community forum. A very well built system to support your queries, questions and give the chance to show your knowledge and help others in their path of becoming Data Science specialists.
Ask
Anybody can ask a question
Answer
Anybody can answer
Vote
The best answers are voted up and moderated by our team

Difference between one-sided and two-sided p-values

Difference between one-sided and two-sided p-values

Super Learner
1
Vote
1
Answer

Hi,
What is the difference between one-sided and two-sided values? And what are they exactly?

1 Answer

365 Team
0
Votes

Hello Tess,
 
We’re glad that you reached out.
 
If the alternative hypothesis is (say for test on one mean) Ha: µ < 50 or Ha: µ > 50 we have one sided test. For Ha: µ > 50 the direction is to the right (right-tailed test). For Ha: µ < 50 the direction is pointing to the left (left-tailed test). On the other hand, the alternative hypothesis Ha: µ ≠ 50 does not specify the direction, towards right or left hence we have two-sided test.
 
Additionally, for 5% alpha, here are the graphs related to rejection region of one sided and two sided tests.
 

 
You may also want to check on https://www.udemy.com/the-data-science-course-complete-data-science-bootcamp/learn/lecture/10772630#questions/5330818 for more detailed explanation of the sides of the test.
 
Hope this helps.
Best,
The 365 Team