Experiments

What are the 4 main types of experiments?

• Laboratory

• Field

• Natural

• Quasi

What are the 3 experiment designs?

• Independent Groups

• Repeat Measures

• Matched Pairs

What are Lab experiments?

Experiments that take place in very controlled and scientific environments- laboratories.

What are Field experiments?

Experiments that take place in a natural situation so that they reflect the real world.

What are Natural experiments?

Experiments that make observations on naturally occurring situations such as natural disasters.

What are Quasi experiments?

Experiments where the independent variable is based on a pre-existing difference between people that cannot be manipulated such as age or race.

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What is an Independent Group design?

Independent group designs are when participants only take part in one condition each, resulting in needing seperate groups for each condition.

What is a Repeated Measures design?

Repeated measures design is when you have hve one group of participants who do multiple conditions instead of only doing one.

What is a Matched Pairs design?

Matched Pairs design is when participants are paired up based on key shared characteristics such as age or IQ before assigning them to a condition.

Strengths and Weaknesses of Lab experiments:

✓ High reliability due to controlled and standardised environment

✓ Great control over extraneous variables

X low ecological validity

X risk demand characteristics

Strengths and Weaknesses of Field experiments:

✓ high ecological validity

✓ low demand characteristics due to mundane and often covert setting

X less control over extraneous variables

X ethical concerns about lack of consent

Strengths and Weaknesses of Natural experiments:

✓ high ecological validity

✓ allows researchers to study things that would otherwise be completely unethical and impossible to manipulate deliberately

X low reliability as it's hard to replicate these distinct occurrences

X no random allocation because groups are formed by circumstance so participants cannot be randomly assigned

Strengths and Weaknesses of Quasi experiments:

✓ high ecological validity

✓ utilise existing groups which saves time

X hard to establish cause and effect because the IV isn't being directly manipulated

X lack of random allocation makes it hard to determine whether participants were equal at the start due to participant variables

Strengths and Weaknesses of Independent Groups design:

✓ no order effects

✓ low risk of demand characteristics

X participant variables as differences amongst participants may affect results

X number of participants is doubled

Strengths and Weaknesses of Repeated Measures design:

✓ participant variables should be gone as it's the same people

✓ fewer participants needed

X order effects like boredom or fatigue may occur

X demand characteristics risk increase

Strengths and Weaknesses of Matched Pairs design:

✓ no order effects as it's different people in each condition

✓ participant variables are minimised through matching

X need twice as many participants

X time consuming and difficult to find participants who match