types of experiments

What do experiments allow you to see? And how?

Cause and effect

The researcher controls every variable and only changes one variable (IV) at a time

The researcher can then conclude that any change in the variable being measured (DV) is from the IV manipulation alone

What is included in a lab experiment?

Controlled The variables include noise or light or temperature or people coming and going

What are the strengths of LAB EXPERIMET

High controL

• High internal validity

• Easy to replicate

• Can find cause and effect (enough control)

What are the weaknesses of a lab experiment

Lacks ecological validity (can’t really be applied on the outside)

Can suffer from experimenter or participant effects

What is validity

Testing what you intended to test

What is a field experiment?

Have variables and are manipulated by the experimenter

Take place in real world

• What are the STRENGTHS of field experiment

• Still able to show cause and effect

Higher ecological validity

What are the WEAKNESSES OF FIELD EXPEIMENT

Harder to control

So harder to replicate

Some research is impossible outside a lab (for example fMRI scan can only be conducted in a lab use to how dangerous it can be)

What is a natural experiment?

Not set up by the experimenter

Situations that occur naturally

Only measured by a researcher

What are the strengths of a natural expedient

REMARKABLY HIGH ECOLOGICAL

Validity

You can study things that would be unethical to study in the lab (e.g gang violence)

Can study things that can be impossible to create (impact of an earthquake)

What are the weaknesses of natural experiment

Researcher has no CONTROL

IMPOSIIBLE TO REPLICATE

they only occur once)

Do not give cause and effect because their is not enough control to allow the researcher to state that one variable has been caused by another

What is a quasi experiment

Occur whenever the researcher is using an

Independent variable that exists naturally

The iv already exists and the researcher can’t decide ppt to go to a group it is chosen already by the naturally occurring variable

independent variable that exists

What are the most common. Quasi variables

Age

Gender

Ethnicity

Race

Intelligence

CAN OCCUR IN LAB OR FEILD

What are the strengths of a quasi experiment

ONLY WAY TO STUDY NATURALLY OCCURING IVS

WHAT ARE THE WEAKNESSES OF QUASI EXPERIMENT

Researcher has lost some control over deciding IV

Therefore in some way it is not a true experiment

Perhaps CANT make a cause an effect

What 2 experiment methods have cause and effect and why?

LAB AND FIELD

Because the IV and DV and extraneous variables are the most controlled

What is an extraneous variable?

Things that should be controlled to make experiment reliable

What are examples of extraneous variables?

Temperature

Light

The amount of food eaten beforehand or sleep

What could a failure to control the extraneous variables mean?

It could mean that the EV changes the DV instead of the IV

Lack of validity

Which then means he researcher has failed

What is a confounding variable

This happens when the researcher has failed to control a variable

It makes it unclear whether the manipulation of the IV or the uncontrolled EV was responsible for the change in DV

It damages the validity