Chapter 7 - The Experimental Research Strategy Flashcards
What is the goal of the experimental research strategy?
to establish the existence of a cause-and-effect relationship between two variables
To rule out the possibility of a coincidental relationship, an experiment must…
show that changes in one variable are directly responsible for causing changes in the second variable
What are the following four basic elements that an experimental study contains?
Manipulation, Measurement, Comparison, and Control
The research MANIPULATES one variable by…
changing its value to create a set of two or more treatment conditions
A second variable is MEASURED for a group of participants to…
obtain a set of scores in each treatment condition
All other variables are CONTROLLED to be sure that they…
do not influence the two variables being examined
What is an independent variable?
A variable that is manipulated by creating a set of treatment conditions
What are the specific conditions that are used in an experiment called?
Levels
What is a dependent variable?
A variable that is measured in each of the treatment conditions.
All other variables that are not the independent or dependant variables are called what?
Extranous variables
What does an experiment attempt to demonstrate?`
That changing one variable (independent V) causes changes in a second variable (dependent V).
The general purpose of the experimental research strategy can be broken down into TWO specific goals:
- demonstrate that the “cause” happens before the “effect” occurs–manipulates the IV and then observes the DV to see if it also changes
- to show that one specific variable is responsible for changes in another variable–most show that changes are not caused by an extraneous variable
Dr. Jones is interested in studying how indoor lighting can influence people’s moods during the winter. A sample of 100 households is selected. Fifty of the homes are randomly assigned to the bright-light condition where Dr. Jones replaces all the lights with 100-watt bulbs. In the other 50 houses, all the lights are changed to 60-watt bulbs. After two months, Dr. Jones measured the level of depression of the people living in the houses. In this example, how many dependent variables are there?
1 - the level of depression
How do studies using the experimental research strategy differ from other types of research?
Only experiments can demonstrate a cause-and-effect relationship between variables
What are the 2 elements of experimental research that are unique?
Manipulation & Control
If you wanted to investigate the effect of temperature (IV) on appetite (DV) what would you manipulate?
You would manipulate the room temperature
EX.60 degrees for one treatment condition, change it to 70 degrees for another condition, and change it again to 80 degrees for the third condition
In an experiment, what is the purpose for manipulating the independent variable?
It helps establish the direction of the relationship and it helps eliminate the third-variable problem
Research indicates the people who suffer from depression also tend to experience insomnia. However, it is unclear whether the depression causes insomnia or the lack of sleep causes depression. What problem is demonstrated by this example?
The directionality problem
What is a confounding variable?
A third variable that is allowed to change systematically along with the two variables being studied
A study is done to determine whether children prefer sweetened or unsweetened cereal. For one group, the researcher uses a box of colourful sweetened cereal, and for the other group, a box of tan-coloured unsweetened cereal. Results showed that the kids ate more of the sweetened colourful cereal and therefore prefer the sweetened cereal. What is the potential confounding variable?
It is impossible to tell whether the preference for the colourful sweetened cereal is caused by the colour or the sweetness.
What is the difference between extraneous and confounding variables?
There are thousands of other variables that exist within any experiment, an extraneous variable becomes a confounding variable only if it influences the dependent variable
In order to establish a relationship between two variables, it is necessary to eliminate the possible influence of…
Confounding variables
What characteristic is necessary for an extraneous variable to become a confounding variable?
It must change systematically when the independent variable is changed.
