Research Methods LY2012 Lecture 4: Sampling & Selection

Dr Calzada

Interactive Activity (25 min)

!  Population: the complete collection to be studied. For instance:

!  All the people using public transport in Birmingham (approx. 0.5 Million individuals?)

Interactive Activity (25 min)

Interactive Activity (25 min)

What exactly IS a “sample”?

What exactly IS a “sample”?

A subset of the population, selected by either “probability” or “non-

probability” methods. If you have a “probability sample” you simply

know the likelihood of any member of the population being included

(not necessarily that it is “random.”

Interactive Activity (25 min)

!  Sample: a section or part of the population.

!  Random Sample: Each individual in the population has an equal chance to being selected.

!  Stratified Sample: A researcher divides the population into groups based on characteristics, and then the researcher randomly selects from each group based on its size.

!  Quota Sample: A researcher deliberately sets a requirement to ensure a particular group is represented.

!  Purposive Sample: A researcher purposefully focuses on a particular subset of a population.

!  Convenience Sample: Selection of the sample is based on ease of accessibility.

!  Research Question:

We would like to research and measure

how efficient is the Public Transport System

in Birmingham City.

A.- Interactive Activity (25 min) ‘The Research Question’

A.- Interactive Activity (25 min) ‘The Research Question’

!  Research Question:

How should we organize the sampling and the selection according to our

research question?

A.- Interactive Activity (25 min) ‘The Research Question’

A.- Interactive Activity (25 min)

Types How could we apply each kind of sampling in order to gather information from the citizens about their opinion on how

efficient is the Public Transport in Birmingham? Random Stratified

Quota Purposive

Convenience