Experimental Method

Summary

This mini-lecture covers the experimental method, which is the primary research approach used to identify cause-and-effect relationships. The script explains key concepts such as independent and dependent variables, experimental and control groups, and the potential challenges in experimental research, including confounding variables, selection bias, the placebo effect, and experimenter bias. Various examples are provided, demonstrating how different factors, like shirt color or caffeine consumption, can be manipulated and measured in experiments. The lecture also introduces methods for controlling biases, including random assignment, blind studies, and double-blind studies, to ensure reliable and accurate results.

Takeaways

• 😀 The experimental method is the only research method that can identify cause-and-effect relationships.
• 😀 In an experiment, the independent variable is deliberately manipulated to observe its effect on the dependent variable.
• 😀 The dependent variable is measured at the end of the experiment to assess the changes caused by the independent variable.
• 😀 Examples of experiments include testing whether shirt color affects job interviews or if caffeine impacts memory.
• 😀 The experimental group is exposed to the independent variable (treatment), while the control group is not.
• 😀 Confounding variables are other factors that could affect the results, such as clothing style, time of day, or personal traits.
• 😀 Random assignment is crucial to prevent selection bias and ensure equal chances for participants to be assigned to different groups.
• 😀 The placebo effect occurs when a person's response is influenced by their expectations rather than the treatment itself.
• 😀 A blind study prevents participants from knowing whether they are in the experimental or control group to avoid bias in their responses.
• 😀 A double-blind study ensures that both the experimenters and participants are unaware of group assignments to prevent biases affecting results.

Q & A

What is the main purpose of the experimental method?

The experimental method is used to identify cause-and-effect relationships, which is not possible with other research methods that simply describe phenomena.

What are independent and dependent variables?

The independent variable is the factor or condition that is deliberately manipulated in an experiment to observe its effect. The dependent variable is the factor being measured at the end of the experiment to assess the impact of the independent variable.

Can you provide an example of an independent and dependent variable?

In the example 'Does caffeine affect memory?' the independent variable is caffeine, and the dependent variable is memory scores on tests.

How is the experimental group different from the control group?

The experimental group is exposed to the independent variable (i.e., the treatment or manipulation), while the control group is exposed to the same conditions but does not receive the treatment.

What is a confounding variable?

A confounding variable is an external factor that can influence the results of an experiment, other than the independent variable. These need to be controlled to ensure the accuracy of the experiment.

What is an example of confounding variables in an experiment involving shirt color and job interviews?

Confounding variables might include factors like the style of the shirt, whether it's ironed, the interviewer's gender, the time of day, or even the person's hygiene or experience.

What is selection bias, and how can it be avoided?

Selection bias occurs when participants are assigned to groups in a way that introduces systematic differences. It can be avoided by using random assignment, ensuring all participants have an equal chance of being placed in either group.

What is the placebo effect, and how does it influence experiments?

The placebo effect occurs when a participant’s response is influenced by their expectations rather than the treatment itself. It can skew experimental results, so it is controlled by using a blind study, where participants don’t know if they are receiving the real treatment or not.

What is the difference between a blind study and a double-blind study?

In a blind study, participants don’t know if they are in the experimental or control group. In a double-blind study, both the participants and the experimenters are unaware of who is in which group, helping to reduce biases from both sides.

How can experimenter biases affect results, and how are they controlled?

Experimenter biases occur when a researcher’s expectations unconsciously influence the results. These can be controlled by using a double-blind study, where both the researcher and the participants are unaware of group assignments.