Z-Scores and T-Scores

Question 1

What are z-scores used for?

Answer 1

A z-score is used to determine the position of a probability score under a curve, as opposed to an interval or percentage.

Question 2

What is the formula for finding a z-score?

Answer 2

Z = (Xi - Xbar) / Std deviation

Question 3

What are t-scores used for?

Answer 3

T-scores are used for hypothesis testing when σ is unknown. For example:

Do college students really get 8 hours of sleep?

Question 4

What is the formula for a t-test?

Answer 4

S-hat sub xbar = s-hat sub x / sqrt(n)

t = x-bar - μ / s-hat sub xbar

Question 5

How is a hypothesis test performed?

Answer 5

1) The type of test is stated (same/different, comparison)
2) State null (H sub o) and alternative (H sub a)
3) Set significance level (accuracy, usually 0.05)
4) Know your degree of freedom (n-1)