Week 1 Populations and Samples

Question 1

Population

Answer 1

An entire group with at least one variable in common. The variable that is being studied.

Question 2

Sample

Answer 2

A subset of a population. Always chosen from the population and used to represent the population.

Question 3

Why do we use sampling techniques?

Answer 3

Selecting a sample minimises costs an maximises generalisability.

Question 4

What is a representative sample?

Answer 4

It is representative of the population being studied and includes all important characteristics from the population it is drawn from. Can impact the quality of the study.

Question 5

Sampling Frame

Answer 5

Complete list of everyone or everything you want to study

Question 6

Difference between sampling frame and population

Answer 6

Population is general, sampling frame is specific.

Question 7

What are the two sampling methods?

Answer 7

Probability sampling and non-probabiity sampling

Question 8

What is probability sampling?

Answer 8

Simple random sampling method. Can make strong statistical inferences of target population as it is representative of population.

Question 9

Non-probability sampling

Answer 9

Non-random selection. Data collected more easily. Subject selected based on criteria or judgement.

Question 10

Probability sampling method: Stratified sampling method

Answer 10

Used to ensure population can be divided into multiple subpopulations. Ensures sample taken correctly reflects proportion of each subpopulation within population.

Question 11

Cluster sampling method

Answer 11

The population is divided into subgroups (clusters). Each cluster has similar characteristics relevant to the population. Entire subgroups are selected as they are indicative of the population. Participants are randomly selected. Have equal chance of being part of the sample.

Question 12

Types of probability sampling methods

Answer 12

Simple random, stratified, cluster

Question 13

Convenience sampling

Answer 13

Sample conveniently taken from a group of people most accessible to the researcher. May be due to geographical proximity, availability, willingness. Easy and inexpensive way to gather initial data, results may not be generalisable if the sample is not representative of the population.

Question 14

Purposive/Judgement sampling

Answer 14

Deliberate selection of specific individual with certain characteristics/events imperative for research. Often qualitative.

Question 15

Snowballing sampling method

Answer 15

When a population is hard to access, participants recruit acquaintances or people they know to become participants.

Question 16

Non-probability sampling methods

Answer 16

Convenience, purposive/judgement, snowballing

Question 17

Inference

Answer 17

The process of drawing conclusions about population parameters based on a sample that is taken from the population.

Question 18

How does inference differ from causation

Answer 18

Inference is interest in what the sample tells us about the population and how representative the sample is of the population.

Question 19

What are the two types of data classifications?

Answer 19

Categorical and Numerical

Question 20

What are the three types of categorical data?

Answer 20

Ordinal, nominal, binary

Question 21

Describe nominal data

Question 21

Describe ordinal data

Answer 21

Can be ordered e.g. cancer grade types, smoking status