Ch. 4 - Research Design Fundamentals Flashcards
Variable
-Is any event, situation, behaviour, or individual characteristic that can take more than one value (ie. it varies)
What are the 2 basic research designs?
- Non-experimental method
2. Experimental method
Non-experimental method
- With this method, relationships are studied by observing or otherwise measuring the variable of interest
- Important point: BOTH variables are measured when using the non-experimental method
- Using this approach may include asking people to describe their behaviour, directly observing behaviour, recording physiological responses, or examining various public records such as census data
- This method does not help us answer questions about cause and effect
Experimental method
- Involves direct manipulation and control of variables. The researcher manipulates the first variable of interest and then observes the response
- One variable is introduced first to see whether it affects the second variable
Operational definition
-Definition of a concept that specifies the operation used to measure or manipulate the concept
What are the 3 general categories to think of variables?
- Situational variable
- Response variable
- Participant variable
Situational variable
- Describes characteristics of a situation or environment
- Ex. the length of words that you read in a book, the number of people who are squeezed into a classroom, the credibility of a person trying to persuade you, and the number of bystanders to an emergency
-Situational variables can be measured in any design, or manipulated in experimental designs
Response variable
- Operational definitions that involve recording a participant’s reaction to some event
- Ex. reaction time, performance on a cognitive task, and degree of helping a victim in an emergency
- Response variables are measured in either experimental or non-experimental designs
Participant variable
- Describes a characteristic that individuals bring with them to a study
- Ex. cultural background, intelligence, and personality traits such as extroversion
- It is often treated as an independent variable in experimental designs, despite the lack of random assignment
Confounding variables
- Confounds are variables that are intertwined with another variable so that you cannot determine which of the variables is operating in a given situation
- Confounds can result from imprecise operational definitions
4 types of relationships between variables
- Positive linear relationship = both variables increase OR both variables decrease (ie. same direction)
- Negative linear relationship = increases in one variable causes decreases in the other OR decreases in one variable causes increases in the other (ie. opposite directions)
- Curvilinear relationship = both variables increase together, then decrease together (or vice versa) (ie. direction changes at least once). Also called an INVERTED-U RELATIONSHIP
- No relationship = flat line on graph. As one variable changes, the other does not change in any systematic way
Correlation coefficient
-Is the numerical index of the strength of relationship between variables
Mediating variable
- Is a psychological process that occurs between two variables that helps explain the relationship
- A psychological process that occurs between an event and a behavioural response
What are the 2 main problems preventing researchers from making causal statements when the non-experimental method is used?
- It can be difficult to determine the direction of cause and effect
- The THIRD-VARIABLE problem - that is, extraneous variables may be causing an observed relationship
Third-variable problem
-When describing the relationship between two variables, a third variable is any other variable that is extraneous to the 2 variables of interest
Third variables vs confounds
-Third variables cause the apparent relationship between two other variables, whereas confounding variables are intertwined with another variable in your study so that you cannot tell which is at work
Independent variable
- In experimental methods, the variable that is manipulated to observe its effect on the dependent variable
- Always placed on the horizontal X-axis of a graph
Dependent variable
- The variable that is measured
- The variable that is the participant’s response to, and dependent on, the level of the manipulated independent variable
- Always placed on the vertical Y-axis of a graph
Internal validity
- Refers to the ability to draw conclusions about causal relationships from our data
- Internal validity is achieved in experiments by using random assignment to condition and ensuring that only the independent variable of interest changes across conditions
What are the two way to achieve internal validity?
- Experimental control
2. Random assignment
Experimental control
-Treat participants in all groups in the experiment identically so that the only difference between groups is the independent variable
Random assignment
-Controlling for the effects of extraneous variables by ensuring that participants in an experiment are assigned to condition in a manner determined entirely by chance
Field experiment
-An experiment that is conducted in a natural setting, rather than in a lab setting
