PSYC3003 week 5 Application: One-Way Experimental Designs

week 5 Application

PSYC-3003-2,Methods in Psyc Inquiry
Application: One-Way Experimental Designs

Researchers need to make many decisions when planning an experiment. As a psychological researcher, one important determination you need to make is the number of independent variables involved in the study. If there is one independent variable, this would be called a one-way experimental design.

Consider a study that hypothesizes that 8-year-olds, who play educational computer games, score higher on intelligence tests than those who do not play educational computer games. Consider how many aspects you would need to address if you were conducting the study. First, you would need to understand that the independent variable is the game-playing, whereas the dependent variable is the intelligence test.

Next, you would need to determine the levels of the independent variable. In this scenario, suppose there are three levels of play: no play, some play (4 hours a week), and frequent play (8 or more hours a week).

Additionally, you would also need to determine whether the study is a between-participants design or a within-participants design (also known as repeated-measures). A between-participants design uses different groups for each level. A within-participants design uses the same group, and that one group repeats the experiment for each level. The latter would not make sense for this experiment because once children experience 4 hours of play, if they then experienced 8 hours of play, the total would be12 hours.

In this Assignment you apply key concepts related to experimental design to a research study.

To prepare:

• Read the assigned pages from Chapter 10 in your course text.
• You may also review and research materials (hard copies or online) outside this week’s Learning Resources that are relevant to the Assignment, if you wish.
• Read the following study: Researchers are interested in the effectiveness of a particular treatment for insomnia. They contact 50 insomnia sufferers who responded to a newspaper advertisement to participate in the study. Each participant is given a pill with instructions to take it before going to sleep that night. The pill actually contains milk powder (a placebo). The participants are randomly assigned to receive one of two sets of instructions about the pill. One half of the participants are told that the pill will make them feel “sleepy,” and the other half are told that the pill will make them feel “awake and alert.” The next day the participants return to the lab and are asked to indicate how long it took them to fall asleep after taking the pill. The individuals who were told that the pill would make them feel sleepy reported that they fell asleep faster than the participants who were told the pill would make them feel alert. Think about the concepts you read about this week on one-way experimental design and how they apply to the above study.

The Assignment (1–2 pages):

With the study in mind, please do the following:

• Identify the independent and dependent variables. Indicate the number of levels in the independent variable and describe each level.
• Indicate whether the research used a between-participants or a within-participants research design. Justify the rationale behind your identification.
• Presume a third condition was added to the present study. In this condition, the participants are not given any information about the effects of the (placebo) pill. Next, suppose an Analysis of Variance (ANOVA) was conducted. Briefly interpret, in your own words, what it would mean if theFwas significant for this study.