Extra definitions

Question 1

Define ‘quota sampling’

Answer 1

• Opportunity sampling
  - Taking whom ever is there at the time
  - and having no control over who is in the sample
• but being able to choose who you want in your sample, e.g. 50 boys and 50 girls

Question 2

What are the advantages and disadvantages of non-random sampling?

Answer 2

• Time
• Biased
• Cost
• Sample size

Question 3

Define ‘absolute risk’

Answer 3

The chance/risk of an event happening`

Question 4

Define ‘relative risk’

Answer 4

The chance/risk of an event happening compared/relative to the chance/risk of another event happening

Question 5

What is the formula for relative risk?

Answer 5

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

Question 6

Addition formula for probability

Answer 6

P(A U B) = P(A) + P(B) - P(A n B)

P(A or B) = P(A) + P(B) - P(A and B)

Question 7

Multiplication formula for probability

Answer 7

P(A n B) = P(A) x P(B|A)

P(A and B) = P(A) x P(B given that A has happened)

Question 8

What is true for 2 independent events?

Answer 8

P(B|A) = P(B)

P(B given that A has happened) = P(B)

Question 9

What is true for 2 mutually exclusive events?

Answer 9

P(A n B) = 0

P(A and B) = 0

Question 10

Define ‘ordinal data’

Answer 10

Data that can be assigned to numerical ranks

Question 11

Define ‘sampling frame’

Answer 11

A list of the sample

Question 12

Define ‘sampling unit’

Answer 12

A single member of a sample