Psychological Investigations Experiments

http://www.holah.co.uk/quiz/experimentalmethodsreview.htm

Lesson objectivesWhat is a target population?Identify and describe different sampling methodsReplicate sampling methods using

Discuss strengths & weaknesses of different sampling techniques

Recap on key terminologyUpcoming assessment briefing

Target PopulationsPsychologists are interested in making ‘general statements’

about behaviour.We can’t test every single person in the world, so

psychologists take a sample of people and try and generalise their findings to the population.

A psychologist may be interested in a particular group of people, e.g. Drinking behaviour in 16-19 year olds living in the UK.

This would mean that all 16-19 years in the UK would be the TARGET POPULATION.

Target PopulationsA sample can be collected by psychologists in a number

of different ways.You need to be able to consider which of these sampling

methods are the best to use. Obviously it will depend on the type of research being conducted.

Random Sampling

Opportunity Sampling

Volunteer Sampling

Stratified Sampling

Skittles Sampling

Record the number of different coloured Smarties that you collect for each type of sampling.

Random samplingEvery member of the target population has an equal

chance of being selected.Every Skittles has an equal chance of being selected

How do you think we could select 5 Skittles from our

packet at random?

Systematic SamplingA systematic sample involves the researcher choosing the

nth person on the list.E.g. You may chose every 5th person from your Psychology

class register

Show me a systematic sample of every 3rd Skittle in your

packet.

Opportunity SamplingAn opportunity sample uses participants who are

available at the time of the research being conducted.E.g. You may chose the first students that pass you in the

corridor

Without much thought tip your Skittles onto the table and select the 6 Skittles that are nearest to

you

Volunteer Sampling

GreenSkittlesWantedHow many green skittles do you

have?

We’ll presume they all volunteer to take part in our study.

Extension TasksScenario 1:A psychologist wants to conduct research into healthy eating habits in 16-19 year old students through questionnaires.

Where should she get her sample from?What type of sampling methods would be best to use and why?

Extension TasksScenario 2:A psychologist wants to investigate whether violence on TV can influence young children to be aggressive.

Where should he get his sample from?What type of sampling method would be best to use and why?

Extension TasksScenario 3:A psychologist is researching whether Psychology students have better memories than Economics Students.

Where should she get her sample from?What type of sampling methods would be best to use and why?

Extension TasksYes/No game

Students to stick given experiment key concept to their foreheads and in groups of 5 have to ask questions to the rest of their group to decide what concept they are. Questions can only be answered using ‘yes’ or ‘no’

You say we pay

INDEPENDENT VARIABLES

AIM

EXTRANEOUS VARIABLES

FIELD EXPERIMENTS

NULL HYPOTHESIS

REPEATED MEASURES

MATCHED PAIR DESIGNS