AS Level Stats

Question 1

Census (advantages and disadvantages)

Answer 1

Measures every member of a population
Very accurate result but may be very expensive and may destroy

Question 2

Sampling units

Answer 2

Individuals of a population

Question 3

Sampling frame

Answer 3

List of sampling units

Question 4

Simple random sampling (advantage disadvantage)

Answer 4

Give everything same chance of being selected. A random number or lottery sampling. Bias free but needs sampling frame

Question 5

Systematic Sampling (advantages and disadvantages)

Answer 5

Take every kth unit. pick a random number between 1 and k for starting point.
Very quite to use but must use sampling frame

Question 6

Stratified sampling (advantages + disadvantages)

Answer 6

Sample represents groups of a population. Then use random/lottery sampling. Good represent population. Must be in strata

Question 7

Quota sampling (A +D)

Answer 7

Strata filled with interviewer or researcher
No sampling frame needed. Not random so bias

Question 8

Oppurtunity sampling ( A + D)

Answer 8

Quota is filled by those available at time.
Easy and cheap. Unlikely to be representative.

Question 9

Types of data

Answer 9

qualitative ( Non numberical)
Quantitative

Question 10

When is the large data set from

Answer 10

May-Oct ( 87 - 15)

Question 11

X with bar on top

Answer 11

Mean

Question 12

Sigma Squared

Answer 12

Variance

Question 13

How to calc variance

Answer 13

Mean of the squares minus square of means

Question 14

Standard devation

Answer 14

Sigma - Root variance

Question 15

Venn Diagram mutually exclusive means

Answer 15

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

Question 16

Independent

Answer 16

P(A and B) = P(A) x P(B)