14 Jun DESCRIBE THE POSTTEST-ONLY DESIGN AND THE PRETEST-POSTTEST DESIGN, INCLUDING THE ADVANTAGES AND DISADVANTAGES
Define confounding variable, and describe how confounding variables are related to internal validity.
Describe the posttest-only design and the pretest-posttest design, including the advantages and disadvantages of each design.
Contrast an independent groups (between-subjects) design with a repeated measures (within-subjects) design.
Summarize the advantages and disadvantages of using a repeated measures design.
Describe a matched pairs design, including reasons to use this design.
Page 162IN THE EXPERIMENTAL METHOD, THE RESEARCHER ATTEMPTS TO CONTROL ALL EXTRANEOUS VARIABLES. Suppose you want to test the hypothesis that exercise affects mood. To do this, you might put one group of people through a 1-hour aerobics workout and put another group in a room where they are asked to watch a video of people exercising for an hour. All participants would then complete the same mood assessment. Now suppose that the people in the aerobics class rate themselves as happier than those in the video viewing condition. Can the difference in mood be attributed to the difference in the exercise? Yes, if there is no other difference between the groups. However, what if the aerobics group was given the mood assessment in a room with windows but the video-only group was tested in a room without windows? In that case, it would be impossible to know whether the better mood of the participants in the aerobics group was due to the exercise or to the presence of windows.
CONFOUNDING AND INTERNAL VALIDITY
Recall from Chapter 4 that the experimental method has the advantage of allowing a relatively unambiguous interpretation of results. The researcher manipulates the independent variable to create groups and then compares the groups on the dependent variable. All other variables are kept constant, either through direct experimental control or through randomization. If the groups are different, the researcher can conclude that the independent variable caused the results because the only difference between the groups is the manipulated variable.
Although the task of designing an experiment is logically elegant and exquisitely simple, you should be aware of possible pitfalls. In the hypothetical exercise experiment just described, the variables of exercise and window presence are confounded. The window variable was not kept constant. A confounding variable is a variable that varies along with the independent variable; confounding occurs when the effects of the independent variable and an uncontrolled variable are intertwined so you cannot determine which of the variables is responsible for the observed effect. If the window variable had been held constant, both the exercise and the video condition would have taken place in identical rooms. That way, the effect of windows would not be a factor to consider when interpreting the difference between the groups.
Our website has a team of professional writers who can help you write any of your homework. They will write your papers from scratch. We also have a team of editors just to make sure all papers are of HIGH QUALITY & PLAGIARISM FREE. To make an Order you only need to click Ask A Question and we will direct you to our Order Page at WriteDemy. Then fill Our Order Form with all your assignment instructions. Select your deadline and pay for your paper. You will get it few hours before your set deadline.
Fill in all the assignment paper details that are required in the order form with the standard information being the page count, deadline, academic level and type of paper. It is advisable to have this information at hand so that you can quickly fill in the necessary information needed in the form for the essay writer to be immediately assigned to your writing project. Make payment for the custom essay order to enable us to assign a suitable writer to your order. Payments are made through Paypal on a secured billing page. Finally, sit back and relax.
About Writedemy
We are a professional paper writing website. If you have searched a question and bumped into our website just know you are in the right place to get help in your coursework. We offer HIGH QUALITY & PLAGIARISM FREE Papers.
How It Works
To make an Order you only need to click on “Order Now” and we will direct you to our Order Page. Fill Our Order Form with all your assignment instructions. Select your deadline and pay for your paper. You will get it few hours before your set deadline.
Are there Discounts?
All new clients are eligible for 20% off in their first Order. Our payment method is safe and secure.