Stats And Mechanics Chapter 1

Question 1

What is a population

Answer 1

A population is all of the items of interest

Question 2

What does a census do

Answer 2

A census observes/collects data from the whole population

Question 3

What does a sample do

Answer 3

A sample observes/collects data from the whole population

Question 4

What is each unit of the population called

Answer 4

Sampling unit

Question 5

What happens when name or number sampling units

Answer 5

The resulting list is called a sampling frame

Question 6

Pros and cons of a cencus

Answer 6

Pros:
Accurate

Cons:
Expensive, time consuming, could destroy all items

Question 7

Pros and cons of a sample

Answer 7

Pros:
Quick, cheap

Cons:
May not be accurate or informative

Question 8

What is a simple random sample

Answer 8

A simple random sample picks items from the population randomly by using a sampling frame. Items are chosen from the sampling frame by using random numbers or by lottery

Question 9

What is systematic sampling

Answer 9

Systematic sampling picks items from the population at regular intervals from an ordered list

Question 10

What is a stratified sample

Answer 10

In a stratified sample the population is split into groups and a sample chosen proportional to the groups site

Number In sample of strata = (number in stratum / number in population) x population sample size

Question 11

Pros and cons of a simple random sample

Answer 11

Pros:
Not biased, chap and easy, each item has an equal chance of being selected

Cons:
Not easy for large populations, sampling frame needed

Question 12

Pros and cons of Systematic sampling

Answer 12

Pros:
Quick and ample, suitable for large samples/populations

Cons:
Sampling frame needed, could be biased if the sampling frame is not random

Question 13

Pros and cons of stratified sampling

Answer 13

Pros:
Sample reflects proportions of population so there is proportional representation

Cons:
Population needs sub-dividing, see simple random sampling

Question 14

What is quota sampling

Answer 14

Selects items/people based on a certain characteristics that reflects the whole population. Usually used by a person completing a questionnaire

Question 15

What is opportunity sampling

Answer 15

Selects items/people thst are available at the time. I.e. someone is in the right place at the right time and has the characteristics you want

Question 16

Pros and cons of quota sampling

Answer 16

Pros:
Small samples can still reflect the population, no sampling frame required, quick/easy/cheap, can compare groups

Cons:
Can introduce bias, groups needed

Question 17

Pros and cons of opportunity sampling

Answer 17

Pros:
Easy and cheap
Cons:
Unlikely to produce a representative sample, relies on the researcher

Question 18

What are the two main types of data called

Answer 18

Quantitative data (numerical)

Qualitative data (non-numerical)

Question 19

What are the two types of quantitative data

Answer 19

Continuous data - van take any value

Discrete data - can only take specific value