P Value from Z-Score Calculator
All you need to know about P Value from Z Score Calculations
p values are either the left or right (1-sided test) or a doubled tail area (2-sided test).
If a tail area is small (small p) a test outcome is unlikely to happen by chance alone and is thus considered 'significant'.
To reject claims (stated in Ho) we need p values to be small (less than 5%) and then accept the alternative (stated in Ha).
Sample Z-Score Problem
What is the P Value given a Z Score z=2 ?
(Ex: Your bowling score is 220 in a league with mean μ=200 and standard deviation σ=10. Then, z=(220 - 200)/10 = 20 /10 = 2)
Solution: To find the tail probability p we enter z=2 above to get .0228=2.28% for 1-sided and .0456=4.5% and reject Ho for both 1 and 2-sided tests at 5% level.
Get it now? Try the above Z Score Calculator a few more times.