3. Z score, normal distribution

How to calculate z scores

score-mean/standard deviation

Z score

a way to measure how far from the mean each of your data values are using a standardized scale

Stat Crunch: calculating z score

1. click stat at the top

2. click calculations

3. click normal distributions

4. type in number

what type of distribution do z scores follow?

normal distribution

normal distribution

• a probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean

• mean=median=mode

• total area under the curve is 1

• the curve never touches the x axis (it is infinite)

What number is considered a significantly high or low Z score?

+2 is considered high

-2 is considered low

probability distribution

• a statistical function that describes all the possible values and likelihoods that a random variable can take within a given range

• simple terms: describes how likely the values of a variable are to occur

continuous distribution

uncountable number of possible outcomes (interval based)

discrete distribution

a countable number of possible outcomes (ex: yes or no questions)