AS-Level Maths: Statistics: Ch1: Data Collection

Question 1

Define ‘Population’:

Answer 1

A Population is the whole set of items that are of Interest.

Question 2

Define ‘Census’:

Answer 2

A Census Observes/Measures Every Member of a Population.

Question 3

Define ‘Sample’:

Answer 3

A Sample is a Subset of the Population intended to Represent the Population.

Question 4

Advantages of ‘Census’: (1)

Answer 4

It should give Completely Accurate Results.

Question 5

Disadvantages of ‘Census’: (3)

Answer 5

-Time Consuming & Expensive.

-Cannot be Used when the Testing Process Destroys the Item.

-Hard to Process Large Quantity of Data.

Question 6

Advantages of ‘Sample’: (3)

Answer 6

-Quick, Cheap & Easy.

-Fewer People have to Respond than in a Census.

-Less Data to Process than in a Census.

Question 7

Disadvantages of ‘Sample’: (2)

Answer 7

-Data may Not be as Accurate as Census.

-The Sample may not be Large enough to Represent Small Sub-Groups of the Population.

Question 8

The Larger the Sample, the More ___ it is.

Answer 8

Accurate.

Question 9

The ___ the Sample, the More Accurate it is.

Answer 9

Larger.

Question 10

Individuals of a Population are known as…

Answer 10

Sampling Units.

Question 11

Sampling Units are often Numbered to form a ___, Called a..

Answer 11

List, Sampling Frame.

Question 12

Define ‘Sampling Frame’:

Answer 12

Sampling Units of a Population are Numbered to Form a List, Called the Sampling Frame.

Question 13

In Random Sampling, every Member of the Population has…

Answer 13

An Equal Chance of being Selected.

Question 14

Random Sampling is ___ of the Population. Why?

Answer 14

Representative. Because Every Member of the Population has an Equal Chance of being Selected.

Question 15

Random Sampling is Representative of the Population. Why?

Answer 15

Because in Random Sampling, Every Member of the Population has an Equal Chance of being Selected.

Question 16

3 Methods of Random Sampling: (3)

Answer 16

-Simple Random Sampling.

-Systematic Sampling.

-Stratified Sampling.

Question 17

What is needed to Carry out a Simple Random Sample?

Answer 17

A Sampling Frame, Usually a List of Sampling Units.

Question 18

What are the 2 Methods to Selecting the Sampling Units from a Sampling Frame? (2)

Answer 18

-RNG

-Lottery Sampling

In both Cases, every Member of the Population is assigned a Number.

Question 19

How are the Sampling Units Chosen in Systematic Sampling?

Answer 19

They are Chosen in a List, at Regular Intervals.

Question 20

In Stratified Sampling, the Population is ___ into Groups, and a ___ ___ is Taken from each.

Answer 20

Divided, Random Sample.

Question 21

Define ‘Sampling Unit’:

Answer 21

Each Individual thing in the Population that Can be Sampled is known as a Sampling Unit.

Question 22

What is ‘Simple Random Sampling’?

Answer 22

Simple Random Sampling is when Every Sampling Unit has an Equal Chance of being Selected.

Question 23

Method of ‘Simple Random Sampling’:

Answer 23

In a Sample Frame, each Sampling Unit is assigned a Number. Then, using RNG, Sampling Units are Chosen.

Question 24

Advantages of ‘Simple Random Sampling’: (3)

Answer 24

-Bias Free.

-Easy & Cheap.

-Each Sampling Unit has an Equal Chance of being Chosen.

Question 25

Disadvantages of ‘Simple Random Sampling’: (2)

Answer 25

-Not Suitable when Population Size is too Large.

-Sampling Frame Needed.

Question 26

What is ‘Systematic Sampling’?

Answer 26

Systematic Sampling is when Sampling Units are Chosen at Regular Intervals from a List.

Question 27

Advantages of ‘Systematic Sampling’: (2)

Answer 27

-Quick & Easy.

-Suitable for Large Samples/Populations.

Question 28

Disadvantages of ‘Systematic Sampling’: (2)

Answer 28

-Sampling Frame Needed.

-Can Introduce Bias if Sampling Frame is Not Random.

Question 29

What is ‘Stratified Sampling’?

Answer 29

Stratified Sampling is when a Population is Divided into Groups (Strata), & a Simple Random Sample is Carried out in Each Group.

Question 30

Advantages of ‘Stratified Sampling’: (2)

Answer 30

-Reflects Population Structures.

-Guarantees Proportional Representation of Sub-Groups within the Population.

Question 31

Disadvantages of ‘Stratified Sampling’: (1)

Answer 31

Population Must be Divided into Strata.

Question 32

What is ‘Quota Sampling’?

Answer 32

Quota Sampling is when the Population is Divided into Groups According to Characteristic.
A Quota of Sampling Units in each Group is set to try and Reflect the Group’s Proportion in the whole Population.

Question 33

Advantages of ‘Quota Sampling’: (4)

Answer 33

-Allows Small Sample to still be Representative of Population.

-No Sampling Frame Required.

-Quick, Cheap, Easy.

-Allows for Easy Comparison between different Sub-Groups in Population.

Question 34

Disadvantages of ‘Quota Sampling’: (4)

Answer 34

-Non-Random Sampling Can Introduce Bias.

-Population Must be Divided into Groups. Can be Costly & Inaccurate.

-Increasing scope of study Increases Time & Cost.

-Non-Responses are Not Recorded.

Question 35

What is ‘Opportunity/Convenience Sampling’?

Answer 35

Opportunity/Convenience Sampling is Sample Taken from People who are found & Studied at the same time.

Question 36

Advantages of ‘Opportunity/Convenience Sampling’: (2)

Answer 36

-Cheap

-Easy

Question 37

Disadvantages of ‘Opportunity/Convenience Sampling’: (2)

Answer 37

-Unlikely to Provide a Representative Sample.

-Highly Dependent on Individual Researcher.