Statistics Chapter 1

Question 1

Population

Answer 1

The whole set of items that are of interest

Question 2

Sample

Answer 2

A subset of the population intended to represent the population

Question 3

Sampling unit

Answer 3

One thing that could be sampled

Question 4

Sampling frame

Answer 4

Sampling units of a population are individually or numbered to form a list called the sampling frame e.g. a register in a school.

Question 5

Census

Answer 5

Data collected from the entire population

Question 6

Advantages and disadvantages Of census

Answer 6

Advantage: Completely accurate result
Disadvantage: time consuming and expensive
Can not be used when best involves destruction
Large volumes of data to process

Question 7

Sample advantages and disadvantages

Answer 7

Advantages: cheap, quick and less data to process
Disadvantages: data may not be accurate, data may not be large enough to represent small sub-groups

Question 8

Random sampling

Answer 8

Giving each unit an equal chance in being chosen in a sample frame

Question 9

how to do Simple random sampling

Answer 9

Each unit in a sampling frame is assigned a number. Use random number generator

Question 10

Advantages and disadvantages of simple random sampling

Answer 10

Advantages: Cheap, easy, bias free / each number has a known equal chance of being selected
Disadvantages: not suitable for a large population, sampling frame needed can introduce bias if the sampling frame is not chosen bias free

Question 11

Systematic sampling

Answer 11

Required elements are chosen at regular intervals in an ordered list
Take every kth element we’re k = pop size / sample size starting at random items between 1 and k.

Question 12

Advantages and disadvantages of systematic sampling

Answer 12

Advantages: simple and easy to use, suitable for large samples
Disadvantages: Sampling frame again needed which can introduce bias

Question 13

Stratified sampling

Answer 13

Divide the population into strata and carry out a simple random sample is carried out in each group.
Used when population is large and naturally divides

Question 14

Advantages and disadvantages of stratified sampling:

Answer 14

Advantages: everything is represented well as there are proportional representations of groups within the population.
Disadvantages: populations have to be classified into distinct strata/ selection of strata can cause bias due to the sampling frame being chosen