Paper 2 - Formulae

Question 1

Weighted mean

Answer 1

(Sum of (weight x value)) / sum of weights

Question 2

Comparative pie charts

Answer 2

Radius 2 / radius 1 = squarerootFrequency2 / squarerootFrequency1

Question 3

Z score

Answer 3

( Value - mean ) / SD

Question 4

Peterson capture recapture

Answer 4

( num in 1st x num in 2nd ) / num in 2nd marked

Question 5

Scatter diagram mean points

Answer 5

( mean of x values, mean of y values)

Question 6

Weighted index number (2)

Answer 6

(Sum of (index number x weights)) / sum of weights

OR

(Current weighted mean price / base year weighted mean price) x 1000

Question 7

Frequency density

Answer 7

Frequency / class width

Question 8

Expected frequency

Answer 8

P(A) x num trials

Question 9

Estimated probability

Answer 9

Successful trials / total num of trials

Question 10

Relative risk

Answer 10

Risk for those in group / risk for those not in group

Question 11

Absolute risk

Answer 11

Successes / total

Question 12

Independency (3)

Answer 12

P(A and B) = P(A) x P(B)
P(at least 1) = 1 - P(none)
P(A or B) = P(A) + P(B) - P(A and B)

Question 13

Index number

Answer 13

( price / base year price ) x 100