Presentation on theme: "Pgs. 25 - 29. GOAL: establish cause and effect relationship between two variables Experiment: Quantitative research (generates numerical data) "— Presentation transcript:
GOAL: establish cause and effect relationship between two variables Experiment: Quantitative research (generates numerical data) Variables Independent Variable (IV): variable being manipulated or changed in the study Dependent variable (DV): the variable that is being measured Variables must be Operationalized, i.e. they must be measurable.
Operationalize your variables by considering each of the following descriptions and deciding whether it is an example of aggression or not. Two men fight over a parking space A football player kicks the ball into a goal Two girls give a boy the “silent treatment” on the playground A man kicks the back of the car when it will not start Three students have a heated debate about whether global warming is happening. Know write a well worded definition of aggression.
The Experimental Hypothesis predicts the relationships between the IV and the DV Null Hypothesis: predicts that there will be no results or that the results will be due to chance. The Control Group has no experimental actions applied to it. WE CAN NEVER PROVE ANYTHING…..WE CAN ONLY DISPROVE. Accept the null hypothesis Refute the null hypothesis Except experimental hypothesis if demonstrate effect due to IV manipulation.
Identify the IV and DV in each of the experimental hypotheses: 1. People are more likely to make a risky decision when they are in a group than when they are alone. 2. An increase in carbohydrates decreases ones ability to concentrate. 3. People will react more quickly to an auditory stimulus than a visual stimulus. 4. Lack of sleep will affect learning new word negatively. 5. Children who have watched a film with a model hitting a blow-up doll will exhibit more aggressive acts toward a blow-up doll than children who have not watched the film.
Laboratory experiments Field experiments Natural experiments
Pros: Easy to control Easy to replicate Cons Artificial environment What is the ecological value? Would your result stand up outside of a lab setting?
Pros Used in Social Psychology Takes place in natural environments, but IV is still manipulated. e.g. Piliavin and Rodin (1969) helping behavior in a New York Subway. Piliavin and Rodin Kitty Genevese 1964 Kitty Genevese The bystander effectbystander effect Cons Cannot control all variables
Natural experiment or quasi – the researchers have no control over the variables Research on stoke patients Cannot change gender Children who have been separated from their parents due to war
Confounding Variables: undesirable variables that influence the relationship between the IV and DV. Artificiality – the situation is so unlikely that one has to wonder if there is any validity to the study
Three of the most common confounding variables: Demand characteristics or Hawthorn Effect – participants behave in a manner that they think they should to meet the demands of the study. To overcome – Single Blind control – participants do not know what the study is about. Researcher Bias or observer bias- the researchers sees what he wants to see. To overcome – Double Blind control – the participants & researcher do not know who is in the control group vs. experimental group Participant Variability – sample represents same characteristics Overcome – random sampling
Not all experiments can be carried out, however, data can reveal relationships between two variables = Correlations Correlation – as one variable changes the other variable changes. This does not mean there is a cause and effect. Positive correlation: as X increases Y increases Negative correlation: as X increases, Y decreases Note – no IV is manipulated, thus there is not cause and effect.
1. They are simple and provide a numerical representations of the relationship that can be easily understood 2. They allow the study of a number of variables that cannot be manipulated experimentally.