Ch. 7: The Experimental Research Strategy Flashcards
the experimental research strategy
establishes the existence of a cause-and-effect relationship between two variables
how does the experimental research strategy accomplish its goal?
the experiment manipulates one variable while a second variable is measured and other variables are controlled
true experiment
attempts to show that changes in one variable are directly responsible for changes in a second variable
independent variable
the variable that is manipulated by the research
independent variable in the behavioural sciences
it usually consists of two or more treatment conditions to which participants are exposed
treatment condition
a situation or environment characterized by one specific value of the manipulated variable
how many treatment conditions do expiments contain?
Experiments contain two or more treatment conditions that differ according to the values of the manipulated variable
levels
the different values of the independent variable selected to create and define the treatment conditions
dependent variable
the variable that is observed for changes to assess the effects of manipulating the independent variable
dependent variable in behavioural research
Typically a behaviour or a response measured in a treatment condition
extraneous variables
all the variables in the study other than the independent and the dependent variable
4 basic elements of experimental studies
- manipulation
- measurement
- comparison
- control
manipulation
the researcher manipulates one variable by changing its value to create a set of two or more treatment conditions
measurement
a second variable is measured for a group of participants to obtain a set of scores in each treatment condition
comparison
the scores in one treatment condition are compared with the scores in another treatment condition. Consists of differences between treatments provide evidence that the manipulation has caused changes in the scores
control
all other variables are controlled to be sure that they do not influence the two variables being examined
what studies are considered “real experiments”
ones that satisfy all 4 elements
what elements are unique to experimental studies?
Control and manipulation
how do you determine statistical significance?
you must conduct a hypothesis test and determine that the difference is statistically significant
significant result
the difference is large enough and consistent enough for a hypothesis test to rule out chance as a plausible explanation, and thereby conclude that the difference must have been caused by the treatment
if there is a difference between scores does that mean the treatment has caused the difference?
not necessarily
causation and the third variable problem
- Just because two variables are related doesn’t mean that they have a causal relationship
- It is always possible that a third variable is controlling the two variables and is responsible for producing the observed relation