That Are The Advantages And Disadvantages Of Pretest Only Design And Posttest Design

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University of Phoenix Material

Week Four Homework Exercise

Answer the following questions, covering material from Ch 8–10 of Methods in Behavioral Research:

1. *What is a confounding variable and why do researchers try to eliminate confounding variables? Provide two examples of confounding variables.

Confounding variable, varies along with the independent variable, it occurs when the effect of the independent and uncontrolled variable are intertwined, so that you cannot tell which variable responsible for the observed effect. Confounding variables are variable the researcher failed to take into account.

a. I’m stressed and I get cramps in my knees, and I cannot sleep, but can I not sleep because of the cramps, or because I’m stressed or is it because a dog is barking outside. The confounding variable is the dog barking

b. You have two groups of children, in which you are teaching new math, one group in (a) room with no windows and one (b) room with window that is open. The children in room (a) learns the task however the children in room (b) only 10% learn the task. The confounding variable is the open window

2. *That are the advantages and disadvantages of posttest only design and pretest-posttest design?

Posttest only – Advantage able to assess if group is equivalent, introduces independent variables, able to measure the effects of the independent variable. The disadvantage is time consuming

Pretest-posttest – Advantage is Mortality (drop out factor), assess equivalency of groups, and can select participates for experiment, Disadvantage sensitize participate on study

3. *What is meant by sensitivity of a dependent variable?

The ability to be sensitive to detect differences between groups,

4. *What are the differences between an independent groups design and a repeated measures design?

Independent group design is where different participates are assigned to each of the conditions using random assignment, where as in repeated measures design the same individuals will participate in both conditions

5. *How do an experimenter’s expectations and participant expectations affect outcomes?

The experimenter’s usually is aware of the purpose of the study and may develop ideas how the participate should act, and this can turn into a bias, whereas the participates expectations of the hypothesis that they will do whatever is necessary to confirm the hypothesis

6. *Provide an example of a factorial design. What are the key features of a factorial design? What are the advantages of a factorial design?


No Caffeine 200mg 400mg Caffeine Caffeine

No Alcohol Response time score Response time Score Response time score

Alcohol Response time score Response time score Response time score

Note; The purpose is to determine how different combinations of alcohol and caffeine will affect response times in a simulated emergency driving situation

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Key features –
1. Knowledgeable questioner-misleading questions
2. Unbiased question
3. Naïve questioner-misleading question
4. Unbiased questions

Advantages – can analyze both variables at the same time in one design, saving time and money.

Disadvantages Reduced probability, Higher confidence levels, confounding on effects

7. *Describe at least four different dependent variables.

1. Interested in how stress affects the (heart rate-DV) in humans
2. How running will decrease the (stress-DV)
3. Doing a sleep study however the (dogs are barking-DV) in the house
4. How driving and drinking alcohol with affect your (reaction time-DV)

8. *What are some ways researchers can manipulate independent variables?

You construct an operational definition of the variable; Stage