Quantitative Research Methods

Conditions for true experiments

1. Extraneous variables controlled

2. Happens in a controlled environment

3. Random allocation to conditions

3 experimental designs

1. Independent samples

2. Repeated measures

3. Matched pairs

Independent samples

Participates randomly allocated into groups and only experience one condition

Repeated measures

All participants experience all conditions

Matched pairs

Participants matched by relevant criteria, then allocated into different conditions.

Independent samples P&C

Pros: Lowers participant expectancy effect and order effects

Cons: Participant variability could influence results

Participant expectancy effect

When participants suspect the results or aims therefore alter their behavior

Order effects

When doing on or more task, the order in which they are presented may affect the result

Repeated measures P&C

Pros: Limits participant variability

Cons: Participant expectancy effect and order effects may influence results

Matched pairs P&C

Pros: Controls hidden biases, limits participant variability

Cons: Harder to design and plan, selection bias

How to control for order effects

Counterbalancing by randomizing order or placebo

Researcher bias

Researches may unconsciously interpret results differently or give unwanted cues

Single blind design

When the participant does not know which group they belong to

Double blind design

When neither the participant nor the researcher knows what group they belong to

Internal validity

The extent to which the evidence found shows the change in DV is due to manipulation of the IV

4 extraneous variables

1. Order effect

2. Researcher bias

3. Participant variability

4. Participant expectancy

4 controls

1. Random allocation

2. Single blind design

3. Double blind design

4. Counterbalancing

Field experiment

Change in DV due to manipulation of IV measured in a naturalistic setting.

See how people act in real-life situations.

Ecological validity

How well can research findings be generalized to real world, every day situations.

Quasi experiments conditions

1. Random allocation is not possible

2. Not all EVs can be controlled

3. IV cannot be generally manipulated

Natural experiment

An experiment where the IV is naturally occurring

4 research methods

1. True experiment

2. Quasi experiment

3. Field experiment

4. Natural experiment

Correlational studies

Explore association between variables, high in external validity.

Population validity

The extent to which findings could be generalized to other groups of people

Ecological validity

The extent to which findings could be generalized to real-world settings

Temporal validity

The extent to which findings could be generalized to different time eras

Case study

An in-depth investigation of a person or small group conducted over a long period of time using a range of different methods.

Case study P&C

Pros: Can explore highly unique situations

Cons: Case studies are hard to replicate, no point in generalizing