Statistics Chapter 1

Question 1

What is a population

Answer 1

It is the whole set of items that are of interest

Question 2

What is a census

Answer 2

It is something that observes or measures every member of a population

Question 3

What is a sample

Answer 3

It is a selection of observations taken from a subset of the population which is used to find out information about the population as a whole

Question 4

What are the advantages and disadvantages of a census

Answer 4

It gives accurate results

Time consuming
Cannot be used when the test destroys the item
Expensive

Question 5

What are the advantages and disadvantages of a sample

Answer 5

Less time consuming
Fewer people have to respond
Less data to process

May not be as accurate
May not be large enough to give info on small sub-groups

Question 6

What are sampling units

Answer 6

Individual units of a population

Often named or numbered

Question 7

What is a sampling frame

Answer 7

It is a list of the sampling units normally named or numbered

Question 8

What is random sampling

Answer 8

It is a method to getting info and means every member of the population has the same chance of being selected and removes bias

Question 9

What types of random sampling are there

Answer 9

Simple random sampling
Systematic sampling
Stratified sampling

Question 10

What is simple random sampling

Answer 10

A simple random sample of size n is one where every sample of size n has an equal chance of being selected

Question 11

What are the 2 ways a simple random sample can be done

Answer 11

Generating random numbers
Lottery sampling - draw names out a hat

Question 12

What is systematic sampling

Answer 12

It is where the required elements are chosen at regular interval from an ordered list

The first person should be chosen at random and then use the interval

Question 13

What is stratified sampling

Answer 13

It is where the population is divided into mutually exclusive strata (e.g. males and females) and a random sample is taken from each

The proportion of each strata should be the same

Question 14

How is the number of people sampled in a stratum calculated

Answer 14

= number in stratum/Number in population x overall sample size

Question 15

What are the advantages and disadvantages of simple random sampling

Answer 15

Free of bias
Each sampling unit has a known and equal chance of selection

Sampling frame needed

Question 16

What are the advantages and disadvantages of systematic sampling

Answer 16

Quick to use
Suitable for large samples and large populations

A sampling frame is needed
It can introduce bias if the sampling frame is not random

Question 17

What are the advantages and disadvantages of Stratified sampling

Answer 17

Sample accurately reflects the population structure
Guarantees proportional representation of groups within a population

Population must be clearly classified into distinct strata
Selection within each stratum suffers from the same disadvantages as simple random sampling

Question 18

What are the types of non-random sampling

Answer 18

Quota sampling
Opportunity sampling

Question 19

What is quota sampling

Answer 19

It is where an interviewer or researcher selects a sample that reflects the characteristics of the whole population

Question 20

What is opportunity sampling

Answer 20

It consists of taking the sample from people who are available at the time the study is carried out and who fit the criteria you are looking for

Question 21

What are the advantages and disadvantages of Quota sampling

Answer 21

No sampling frame required
Quick, easy and inexpensive
Allows for easy comparison between different groups

Can introduce bias
Population must be divided into groups which is costly and inaccurate
Making the study bigger means more groups and more expenses
Non-responses are not recorded

Question 22

What are the advantages and disadvantages of Opportunity sampling

Answer 22

Easy to carry out
Inexpensive

Not providing a representative sample
Dependant on individual reseacher

Question 23

What are variable or data with numerical observations called

Answer 23

Quantitative variable or quantitative data

Question 24

What are variable or data associated with non-numerical observations called

Answer 24

They are called qualitative variable or qualitative data

Question 25

What is a variable that can take any value in a give range called

Answer 25

Continuous

e.g. Time

Question 26

What is a variable that can take only specific value in a give range called

Answer 26

Discrete variable

Number of people in a family