1 - DATA Collection

Question 1

What is the population

Answer 1

The full set of items (people or objects) that you are studying

Question 2

What is a census

Answer 2

Data collection that measures the whole population

Question 3

What is a sample

Answer 3

A selection of observations taken from the population

It is taken to find information about a population as a whole

Question 4

Advantages and disadvantages of a census

Answer 4

A:
Completely accurate results

D:
Time consuming
Cant be used if testing destroys the item.
Hard to proxess large quantities of data

Question 5

Advantages and disadvantages of a sample

Answer 5

A:
Less time consuming and less expensive
Fewer people have to respond
Less data to process

D:
Less accurate data
Sample may not be large enough to be representative

Question 6

What are sampling units

Answer 6

Individual units within a population

Question 7

What is a sampling frame

Answer 7

A list (typically numbered) of all the sampling units

Question 8

What is simple random sampling

Answer 8

A method of sampling in which every sample has an equal chance of being selected

This is done through generating random numbers or lottery sampling

Question 9

What is lottery sampling

Answer 9

A method of simple random sampling where the members of a sampling frame are written on tickets and placed in a ‘hat’.

Tickets are randomly drawn out to fill the sample

Question 10

What are examples of random sampling

Answer 10

Simple random sampling
Systematic sampling
Stratified sampling

Question 11

What is systematic sampling

Answer 11

A random sampling method where sampling units are selected at regular intervals from an ordered list

If the sample size is 20 in a population of 100 (100/20) take a data point every 5 units

The first sampling unit is selected randomly (use a random number generator)

Question 12

What is stratified sampling

Answer 12

Random sampling where the population is divided into mutually exclusive strata, and a random sample is taken from each

Question 13

What does mutually exclusive mean

Answer 13

Factors that cant be true at same time

Question 14

How is the sample required for each strata calculated (in stratified sampling)

Answer 14

Sample of strata= (number in stratum ÷ number in total population) × total sample size

Question 15

What are strata

Answer 15

Distinct subgroups in a population

( with a population size that is useful for comparisons)

Question 16

Advantages and disadvantages of simple random sampling

Answer 16

A:
Free of bias
Easy and cheap to implement in small populations / smaples
Each sampling unit has an equal chance of selection

D:
Sampling frame is needed
Not suitable with a large population, as it would be time consuming and expensive

Question 17

Advantages and disadvantages if systematic sampling

Answer 17

A:
Simple and quick to do
Suitable for large samples / populations

D:
Sampling fram required
It can introduce bias, if the sampling frame is not random

Question 18

Advantages and disadvantages of stratified sampling

Answer 18

A:.
Accurately reflects the population structure
Guarantees proportional representation of groups in a population

D:
Population must be clearly classified into distinct strata

(Selection within each stratum has the same disadvantages as simple random)

Question 19

What is quota sampling

Answer 19

Selecting a sample that reflects the characteristics of the whole population

(Interview people to place them in a specific group due to characteristics)

Question 20

What is opportunity / convenience sampling

Answer 20

Taking a sample from people who are available at the time of the study and people who your criteria fit

E.g first people you meet at a supermarket who are carrying shopping bags

Question 21

Advantages and disadvantages of quota sampling

Answer 21

A:
Small sample that is representative of the population
No sample frame needed
Quick, easy, inexpensive
Allows for easy comparison between groups

D:
Non random sampling can introduce bias
Population must be divided into groups which could be inaccurate
Possibility of non-repsonse (takes up time)
The larger the study, the more groups, the longer the time takes

Question 22

What are examples of non-random sampling

Answer 22

Quota sampling or opportunity sampling

Question 23

What is the main difference between random and non-random sampling

Answer 23

In non random sampling you are puting people directly into groups

In random sampling they are already in groups

Question 24

What are the advantages and disadvantages of opportunity sampling

Answer 24

A:
Cheap
Easy to carry out

D:
Will not be representative of the population
Dependent on the judgement of the researcher

Question 25

What is quantitative data

Answer 25

Data or variables associated with numerical values

Question 26

What is qualitative data

Answer 26

Data ot variables associated with non-numerical observation

Question 27

What is a continuous variable / data

Answer 27

A variable / data that can take any value in a range

Question 28

What is a discrete variable / data

Answer 28

Variables / data that can only take specific values in a given range

Question 29

If continuous data is in a grouped frequency table that is not given using inequalities, what would the lower and upper class boundaries be E.g class 30 to 31

Answer 29

As continuous data can be a decimal, we have to assume it is all being rounded to the nearest 0.5 The lower boundary would be 29.5 The upper boundary would be 31.5 The actual class width is 2

Question 30

If AGE is in a grouped frequency table that is not given using inequalities, what would the lower and upper class boundaries be E.g 20-30

Answer 30

Age is always rounded down This means that the true lower boundary is 30 The true upper boundary is 31