Question

Define type 1error

What is the difference between t- Test, and z test

Answer 1

Error Table		Null Hypothesis is
		True	False
Decision about Null Hypothesis is,	Don't Reject	Correct inference (true negative) (probability = 1−α)	Type II error (false negative) (probability = β)
	Reject	Type I error (false positive) (probability = α)	Correct inference (true positive) (probability = 1−β)

Both Z test and t test are assumed to have a normally distributed data, z test is used when there large sample size (n>30), while t test is used when there is small sample size (n<=30).

Z test is mostly used when the standard deviation is known.