The Normal distribution

Question 1

Variance formula

Answer 1

Mean of the squares minus the square of the mean

Question 2

Two tailed test significance levels

Answer 2

Halve the level at the end you are testing

Question 3

Test Statistic

Answer 3

Result that is calculated from the sample (e.g if coin tossed 8 times to find number of heads, C, test statistic would be C

Question 4

What are the parameters for the normal distribution?

Answer 4

μ and σ², meaning population mean and population variance

Question 5

Features of the normal distribution graph

Answer 5

Bell-shaped, mode=median=mean, symmetrical, area under curve = 1, points of inflection one σ away from mean

Question 6

What is are the parameters in the binomial approximation?

Answer 6

μ=np, σ=√(np(1-p))

Question 7

When can the binomial distribution be approximated to a normal one?

Answer 7

n is large, p is close to 0.5

Question 8

In a standard normal distribution, what are the parameters?

Answer 8

(0,1)

Question 9

What does the percentage points table tell you?

Answer 9

Values of z and p such that P(Z>z) = p

Question 10

How to standardise?

Answer 10

Z = (X - μ)/σ

Question 11

What estimations can be made of a normally distributed variable?

Answer 11

68% data lies within one standard deviation of the mean, 95% within two and 99.7% within three

Question 12

What is the actual significance level?

Answer 12

The probability that the value will fall in the critical region even if H0 is true.

Question 13

What is the critical region?

Answer 13

The values that if observed, would cause H0 to be rejected.

Question 14

Why do we have to apply continuity corrections?

Answer 14

Turning the discrete binomial into continuous normal

Question 15

How to apply continuity corrections?

Answer 15

If x=6, x lies in 5.5<x<6.5 range

Question 16

What does mu represent?

Answer 16

Population mean