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Flashcards in 6 - Normal Distribution Deck (21):
1

What characterizes a normal distribution?

1. Mean 2. Standard deviation

2

Approximately how many standard deviations are on either side of the mean?

3

3

The _____ is the point of symmetry in a normal distribution.

Mean

4

The standard deviation in a normal distribution is the distance between _____ and _____.

Mean, and the point of inflection

5

Importance of normal distributions (2). 1. 2.

1. Describes many distributions of real data and "chance" outcomes 2. Models many roughly symmetric distributions for statistical inference

6

What do density curves describe?

Continuous probability distributions

7

Normal distributions are a type of ____.

Density curve

8

Normal curves describe:

Normal distributions

9

What determines the SPREAD of a Normal distribution?

Standard deviation

10

How will a normal curve looks with a smaller SD compared to a larger SD?

Smaller SD: taller Larger SD: shorter

11

Typically, do the mean and standard deviation describe the shape of most distributions?

No. Only in a Normal distribution.

12

How can we tell if a distribution is Normal?

By using a Normal Quartile Plot

13

Does this Q-Q plot display a normal distribution?

Q image thumb

No. Right-skewed.

14

Which is left-skewed? Which is right-skewed?

Q image thumb

 

 

A image thumb
15

What rule do all normal distributions follow?

68-95-99.7 rule

16

In a normal distribution, approximately ___% of observations fall within σ of the µ.

68%

17

In a normal distribution, approximately ___% of observations fall within 2σ of the µ.

95%

18

In a normal distribution, approximately ___% of observations fall within 3σ of the µ.

99.7%

19

Formula for z, when standardizing a distribution that has a mean µ, and SD, the standardized value of x is:

z = x - µ / σ

20

What does a z-score tell you?

How many standard deviations the original observation falls away from the mean, and in which direction (+ = how many standard deviations greater than the mean, - = how many standard deviations less than the mean).

21