Maths-Statistics-Data Presentation

Question 1

Mean

Answer 1

Frequency of each data value, over n (the total number of data values).

Question 2

Mode

Answer 2

Most frequently occuring data value.

Question 3

Population

Answer 3

Group of people or items

Question 4

Census

Answer 4

When the population is finite, a census surveys the entire population

Question 5

Advantages + Disadvantages of a census

Answer 5

Adv: Accurate information, because every member sampled
Adv: True representation of population, Unbiased
Dis: For large populations, it takes a lot of time and effort to carry out
Dis: Expensive
Dis: Difficult to make sure all members are surveyed, bias can be introduced if some are missed
Dis: If tested items are used up or damaged, impractical

Question 6

Sample

Answer 6

Examination of just a selection of the population

Question 7

Sampling units

Answer 7

Individual members of the population selected for the sample

Question 8

Sampling frame

Answer 8

A full list of sampling units is called a sampling frame

Question 9

How do you Avoid bias in a sampling frame

Answer 9

Correct population and ensure none of the population is excluded
Selection needs to occur at random
Make sure all your sample members respond

Question 10

Sampling advantages and disadvantages

Answer 10

Adv: Quicker and cheaper than a census, and easier to get hold of all the required information
Adv: Only option when surveyed items are used up or damaged
Dis: Variability between samples
Dis: Easily affected by bias

Question 11

Random Sampling

Answer 11

Give a number to each population member, from a full list of population.
Generate a list of random numbers.
Match these numbers to the population members to select your sample.

ADV: Every member of popluation has equal cahnce of being selected, Completely unbias
DIS: Inconveniant if the population is spread over a large area , might be difficult to track down selected members.

Question 12

Systematic Sampling

Answer 12

Give a number to each population member, from a full list of the population.
Calculate a regular interval to use by dividing the population size by sample size. Generate a random starting point that is less than or equal of the interval
keep adding interval to the starting point to select your sample

ADV: Can be used for quality control, machine can be set up to sample every n items, should be unbiased
DIS: