Z Test For Samples

Question 1

What does Standard Deviation measure?

Answer 1

Error variability in the data:
On average how far scores fall away from the mean
Tells us how “spread out”/noisy our data is
A large standard deviation means there is a lot of error variability in the data

Question 2

What do z scores tell us?

Answer 2

They tell us in one number how close to the mean a score is, relative to the overall variability in the sample

Question 3

How are z scores calculated?

Answer 3

Subtracting the mean from the score (getting the difference) and diving by the standard deviation

Question 4

What information do you need to have to work out the z score?

Answer 4

The single test score, the population mean, and standard deviation

Question 5

What does a z score of 1.96 or greater mean?

Answer 5

There is a less than 5% chance that the score belongs to the null distribution - conclude that the null hypothesis is probably false