Lesson 1 - Experimental methods Flashcards
(16 cards)
What is the independent variable?
The variable that is changed to affect the dependent variable
What is the dependent variable?
The variable that is not changed. You measure this variable.
What is the control control group?
A condition where the independent variable is not manipulated to compare results.
What are extraneous variables?
Outside variables that could affect the dependent variable
What are confounding variables?
Outside variables that have affected the dependent variable
Strengths of lab experiments
- They can be repeated to see if the results are reliable
- The experimenters have a high level of control over the IV. This prevents extraneous variables from becoming confounding variables
- Experimenters can manipulate the IV so they can establish a cause and effect relationship
Weaknesses of lab experiments
- Demand characteristics may occur - guessing the aim of the study
- Participants may behave more positively than normal, called social desirability bias
- High level of control over the IV means that the experiment lacks mundane realism and ecological validity (cannot be applied to other places and contexts)
What are field experiments?
Experiments carried out in the real world, but the IV is still manipulated
Strengths of field experiments
- There is more mundane realism and EV. Reflects every day life better than a lab study
- There can still be manipulation of the IV and cause/effect can be established
- It is less likely to result in demand characteristics, as participants may not be aware that they are in an experiment. More valid data will be collected
Weaknesses of field experiments
- There is less control over extraneous variables than a lab study and this weakens the validity of the experiment
- You have less control over who is taking part (sample) in the experiment as well as in a lab experiment
- Can be hard to replicate, can be unreliable compared to lab studies
What are natural experiments?
Experiments where you observe naturally occurring IVs. You do not directly manipulate the IV.
Strengths of natural experiments
- High level of mundane realism and ecological validity
- This is favourable when it would be unethical to manipulate the IV by yourself, like stress among men with cholesterol. You cannot stress people out for an experiment
Weaknesses of natural experiments
- Low control over extraneous variables, can affect validity
- They are very difficult to replicate and they are therefore unreliable.
- It is difficult to establish cause and effect
What is a quasi experiment?
This is when you want to see the effect of a naturally occurring IV on the dependent variable. Usually occurs in a lab setting
Advantages of a quasi experiment
- high level of control.
- effects of extraneous variables are minimised, so we can be more confident in that the IV has an effect on the DV.
- Replication is likely due to the strict controls so it is easier to replicate to test reliability of findings.
Disadvantages of quasi experiments
- Lack of ecological validity because the setting is artificial and may not be a reflection of real life behaviour.
- Demand characteristics may arise as the participants may guess the aim of the study. This can render the results invalid
