Year 2 Statistics

Question 1

What does y=axn equal to

Answer 1

log y = log a + nlog x

Question 2

What is the product moment correlation coefficient

Answer 2

It describes the linear correlation between 2 variables
it is between -1 and 1

Question 3

What does it mean when the product moment correlation coefficient is 1 and -1 and 0

Answer 3

1 is a perfect positive linear correlation
-1 is a perfect negative linear correlation
0 is no linear correlation

Question 4

What is A n B

Answer 4

The intersection of A and B

Question 5

What is A u B

Answer 5

It is all of A and B

Question 6

What is A’

Answer 6

Everything but A

Question 7

How can the probability that B occurs given that A has occurred written as

Answer 7

P(B l A)

Question 8

What are the conditions that mean an event is independant

Answer 8

P(A l B) = P(A l B’) = P(A)
P(B l A) = P(B l A’) = P(B)

Question 9

What is the equation for P(AuB)

Answer 9

P(A) + P(B) - P(AnB)

Question 10

What is the equation for P(B l A)

Answer 10

P(BnA)/P(A)

Question 11

What is the area under a continuous probability distribution equal to

Answer 11

1

Question 12

How do you write the normal distribution of X

Answer 12

X ~ N(u, o2)
u= population mean
o2 = population variance

Question 13

What is the normal distribution like

Answer 13

Symmetrical (mean=median=mode)
Bell-shaped curve
Area under the curve equal to 1
Points of inflection at u+o and u-O

Question 14

What is the standard normal distribution

Answer 14

Mean = 0
standard deviation = 1
Z~N(0,1^2)

Question 15

How do you convert from the standard normal distribution

Answer 15

Z = Y - mean / standard deviation

Question 16

What happens when n is large and p is near 0.5 in the binomial distribution X~B(n,p)

Answer 16

It can be approximated by the normal distribution
u=np
o = square root( np (1-p) )

Question 17

What percentage of the data is within 1 standard deviation of the mean

Answer 17

68%

Question 18

What percentage of the data is within 2 standard deviation of the mean

Answer 18

95%

Question 19

What percentage of the data is within 3 standard deviation of the mean

Answer 19

99.7%

Question 20

What does the product moment correlation coefficient measure

Answer 20

Linear association between 2 variables