Experimental Method & Types

Explain the 3 key features of a true experiment (3)

• IV (Independent Variable)- manipulated by the researchers or differs somehow

• DV (Dependent Variable) - measured by the researchers

• EV (Extraneous Variables) - controlled by the researchers

How are field/natural experiments different from a laboratory experiment (2)

• Field/Natural experiments are carried out in the real world

• While Laboratory experiments are in a controlled setting

How are Field experiments different from Natural experiments (2)

• Field experiments involve manipulation of an IV

• While in Natural experiments they are due to events

How are Natural experiments different from Quasi- experiments (2)

• In Natural experiments the IV varies due to an event

• In Quasi- experiments the IV varies due to group differences (pre-existing)

Why are quasi- experiments unusual compared to other types (2)

• No change in an IV - it’s pre-existing

• No specified location - can take place anywhere

Compare how well: Lab, Field, and Natural experiments can control EV’s

• Order: Natural → Field → Lab (best)

• In Lab experiments there is a controlled environment to monitor and control EV’s

• In Field experiments there is some control from the researchers but there can be unexpected events

• There is no control at all in Natural experiments

Compare how likely demand characteristics will appear in: Lab, Field, and Natural experiments

• Order: Field & Natural → Lab (most likely)

• Lab: participants know they are in an experiment

• Field: participants usually don’t know they are in an experiment but may question an unusual situation

• Natural: participants feel normal since researchers aren’t manipulating anything

Compare the ecological validity in: Lab, Field, and Natural experiments

• Order: Lab → Field → Natural (best)

• Lab: artificial situation

• Field: natural behaviour usually occurs

• Natural: real-life

Compare the population validity in: Lab, Field, and Natural experiments

• Depends (Contextual)

• Lab: can actively recruit representative samples but rarely do since participants have to volunteer

• Field & Natural: measure behaviour in participants who wouldn’t normally volunteer in lab studies

Identify what Quasi- experiments can/can’t establish about group differences

• that there are group differences

• But can’t explain why

Compare how consent is obtained in (+ difficulty) : Lab, Field, and Natural experiments

• Lab: participants are recruited for study (easy)

• Field: participants don’t usually consent as they are unaware (hard)

• Natural: participants are either recruited or data is collected without knowledge/consent (depends)