A hypothesis is a precise and testable statement of the researchers prediction of the outcome of the study.
Independent Variable (IV) & Dependent variable (DV
IV the variable that is manipulated to affect the outcome.
DV the variable that is measured.
Lab experiments are experiments that tke place in controlled environment.
- Easy to replicate
- Quantitive data
- May induce PP's to change their behaviour as a result of demand characteristics.
- Has low Ecological Validity
Ecological validity is how well an experiment can be applied to a real world setting.
Demand Characteristics are elements of an experiment that may cause PP's to act unnaturally and produce unrealistic data.
A field experiment is an experiment which takes place in a real life situation so as data created can be as close to natural behaviour as possible.
- Behaviour created is more likely to be real and thusly has a high ecological validity.
- There is less chance of demand characteristics.
- Deception is created because PP's o not know that they are in an experiment.
- So no consent is given by the PP's.
A natural experiment is one in which the variable has occured naturally and is then taken advantage of by the scientist.
- Natural experiments allow researchers to be able investigate things which would usually be unethical.
- Less chance for demand characteristics.
- Less control for the researcher.
Experimental group & Control Group
Experimental Groups are the group which experiences the independent variable.
Control groups on the other hand experience nothing of the sort. The two are then compared to see if any differences have occured.
The way the experiment is to be done mainly in the area of how the groups are to be split.
Independent groups design
The independent groups design is assigning PP's to each group randomly.
- Quickest and easiest of any design
- People naturally vary and this can cause differences in their test results
Repeated measures design
This is where each group experiences all conditions.
- No PP variables
- Requires fewer PP's
- Demand charcateristics are more present because the PP may guess the aim of the experiment.
- May produce practice effects.
Matched Pairs design
This is where members of each group are matched together and their results compared.
- No counterbalancing needed
- Expensive and time consuming
- PP variables can still have an affect.
This is where PP's are randomly allocated to each group.
Experiencing both conditions in an experiment may produce order effects. for example they are practiced at the task or bored the second time round.
Reversing the order of the conditions for half the PP's
This is when a selection of people are randomly selected from a target population and take part in the experiment.
- The best sampling technique for an unbiased representation of a target populos
- It can be very time consuming, and impossible for large populations.
This is when PP's who are easily accesible are used.
- Quick and cheap
- Not representative of society.
This means PP's are selected at chosen intervals from a population.
- Fairly cheap and fast
- No bias in selecting PP's
- A hidden order could disrupt the experiment
A sample that is in proportion to the entire population.
- Very representative
- Time consuming and expensive
This is where each PP undergoes the same procedure so as the results are unbiased.
A confounding variable is a variable which affects the outcome experiment in an unwanted way for example....
"Sir the experiment to check how many times people pet ducks in a minute has gone horribly wrong"
"How so Johnson?"
"It's the ducks sir, their....... their....."
"Spit it out Johnson!"
"Their eating people..."
"...........My god I can't believe we never took into account this variable it's so confounding!"
PP's should all be given exactly the same instructions so as to make an experiment fair... When we give all the PP's the same instructions it is because they are standardised. These reduce confounding variables.
Mean, Mode and Median
Mode - The mode is the most frequently occuring score.
Mean - The average of the scores.
Median - Is the exactly middle score.
The range is the difference between the highest and lowest scores.
Ethics are a set of rules which must be followed so as to keep PP's happy or at least alive...... These rules must be taken into account.
Confidentiality - Storing PP's names as initials
Observations - You must respect PP's privacy.
Withdrawal - All PP's should be allowed to withdraw at any time during the experiment.
Distress - You cannot put PP's through significant amounts of stress.
Deception - It is unethical to deceive PP's
Consent - Consent must be collected from PP's
Debriefing - All PP's must be debriefed after the experiment.