4-Normal Distributions Flashcards
What are normal distributions also called ?
Gaussian distributions
What is the 34-14-2 approximation?
It summarizes the approximate proportion of normal distributions in intervals that are one standard deviation (σ) wide.
Approximately 34% of a normal distribution falls between μ and μ + σ, approximately 14% of a normal distribution falls between μ + σ and μ + 2σ, and approximately 2% of a normal distribution lies above μ + 2σ.
True or false? For every probability density function there is a cumulative distribution function
True
Which function have an S shape ?
CDFs
How do you convert every scores into standard scores ?
By converting into z-scores
What does P(x) means in a distribution ?
Proportion of distribution below x
Whats the formula for finding the z scores?
z=(x-mew)/o
What is the standard normal distribution ?
The distribution of z-scores. The standard normal distribution has a mean of μ = 0, a standard deviation of σ = 1, and a variance of σ2 = 1.
Whats the formula for transforming z scores into the original unit ?
x= mew+z(o)
True or false. Converting units into z scores changes the shape
False, it only changes the scale
What happens if you want to find a probability of z-distribution above a certain score.
You retract 1 from the proportion below
In the rule 2 how do you express a randomly choosen score greater than z?
1-P(z) or (-1*z)
In rule 3, how do you express a number between z1 and z2?
P(z2)-P(z1) (taking in consideration that z2 is greater than z1)
In rule 4, how do you express a randomly choosen score outside of the interval of z1 and z2
1 - [P(z2)-P(z1)]
In rule 1, how do you express a randomly choosen score under z?
P(z)
