Research Methods - Variables and Types of Experiments

Research Methods - Variables and Types of Experiments

​CIE Psych 9990 - AS

by Violet Bawab

​​Why do psychologists do research?

​

• To test ideas and discover supporting evidence 

• Effectively conducted and well planned research is TRUST WORTHY 

​Experiments are defined as: an investigation which looks for a cause and effect relationship 

​How ?

• One variable (Independent variable) is responsible for a change in another variable (dependent variable) 

  • The IV is manipulated - producing 2 conditions 

  • High and low IV 

  • The effect on the DV is measured 

​Variables

• ​Variables are the factors being measured in an experiment

• ​A psychologist choses to check how various factors affect each other in a specific setting

• ​Can you think of examples?

​Definitions

​Experiment: An investigation looking for a causal relationship in which an independent variable is manipulated and is expected to be responsible for changes in the dependent variable 

​

Independent variable: the factor under investigation in an experiment which is manipulated to create 2 or more conditions (levels) and is expected to be responsible for changes in the dependent variable. 

​

Dependent variable: the factor in an experiment what is measured and expected to change under the influence of the independent variable 

Fill in the Blank

The  _________variable is manipulated to test its effect on the   __________ variable. 

.

Open Ended

Consider a simple experiment you would like to conduct....

What two factors are you exploring a relationship between?

Simply list 1 dependent variable and 1 independent variable. Be ready to explain your choice.

​Correlation ....not causation

​Researchers can very rarely conclude a CAUSATION of one factor with another.....

​

​Why do you think that is the case?

​

Open Ended

What is a correlation and are there any types?

​Other terms to learn

​Extraneous variable:

a variable which either acts randomly, affecting the DV in all levels of the IV or systematically, i.e. on one level of the IV (called a confounding variable) so can obscure the effect of the IV, making the results difficult to interpret. 

​

​

Participant variables:  

individual differences between participants (such as age, personality and intelligence) that could affect their behaviour in a study. They could hide or exaggerate differences between levels of the IV.

​Other terms to learn

Experimental condition:

one or more of the situations in an experiment which represent different levels of the IV and are compared (or compared to a control condition). 

​

Control condition:

a level of the IV in an experiment from which the IV is absent. It is compared to o

ne or more experimental conditions.

​

​Now it is time to understand different types of experiments....

​There are three types:

​

​1) Lab Experiment

​

​2) Natural Experiment

​

​3) Field Experiment

​In-class task

​During the next 15 minutes, you will be required to prepare a summary of the type of experiment you are assigned as follows:

​

​Team 1 - Lab Experiment - Definition / Features

​Team 2 - Field Experiment - Definition / Features

​Team 3 - Natural Experiment - Definition / Features

​Team 4 - Lab Experiment - Evaluation in terms of Validity

​Team 5 - Field Experiment - Evaluation in terms of Validity

​Team 6 - Natural Experiment - Evaluation in terms of Validity

Ethics in experiments

• ​A participant in a laboratory experiment is likely to know that they are participating in a study and can readily be asked for their informed consent.

• ​informed consent : knowing enough about a study to decide whether you want to agree to participate.

• ​Informed consent means that a participant is giving full written approval to the researcher to participate in an experiment.

Ethics in experiments

• ​A participant in a laboratory experiment is likely to know that they are participating in a study and can readily be asked for their informed consent.

• ​informed consent : knowing enough about a study to decide whether you want to agree to participate.

• ​Informed consent means that a participant is giving full written approval to the researcher to participate in an experiment.

Ethics in experiments

• ​Confidentiality can be respected in all experiments by keeping the participants’ data secure and anonymous, although if the participants are unaware that data has been collected, as in a field experiment, it is important to ensure that they cannot be individually identified, for example by their place of work.

• Confidentiality : The identity of participants should be protected and personal information should not be shared with anyone outside of a study.

Ethics in experiments

• ​Privacy can be respected in laboratory experiments because the tests or questions used are pre-planned, while in field or natural experiments, there is a higher risk of invading participant privacy.

  ​

• Privacy : participants’ emotions and physical space should not be invaded, for example they should not be observed in situations or places where they would not expect to be seen

Ethics in experiments

Deception: for some experiments to yield valid results, some deception (not fully informing participants of the real aim of an experiment) needs to take place. This needs to be followed up by a proper debriefing of participants upon completing a study to ensure they face a minimal level of distress.

​

Deception: Participants should not be deliberately misinformed about the aim or procedure of a study.

Ethics in experiments

Right to Withdraw: Participants should be able to leave a study at any point without any pressure to continue by the researchers.

​

​This is difficult in cases of deception, when a participant is not aware of an experiment to start with and has not given informed consent.

​

​If a participant withdraws from an experiment, their results will not be counted.

Ethics in experiments

Debriefing: giving participants a full explanation of the aims and potential consequences of the study at the end of a study in order for them to leave in a at least as positive a condition as they arrived.

​

This is very important to correct any deception and give participants the chance to ask questions about a study. It is the time when a researcher fully explains the aims of a study and ensures a participant still agrees for their data to be used in the results.

Multiple Choice

What ethical principle means the following:

Informing participants of the full aims of a study and asking for their written approval to participate?

• Debriefing

• Informed consent

• Right to Withdraw

• Deception

Multiple Choice

What ethical principle means the following:

Misleading participants to believe that they are participating in an experiment about food profiles while the researcher is exploring the possibility of adding false memories to their memories. 

• Debriefing

• Informed consent

• Right to Withdraw

• Deception

Ethical Considerations - MindMeister Mind Map

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