Exam 12: Designing, Conducting, Analyzing, and Interpreting Experiments With Multiple Independent Variables

In the following study, participants were instructed to press a button on a computer keyboard as soon as they detected a tone through their headphones. Half of the time, the computer screen flashed a light at the exact moment the tone was presented and the other half of the time there was no flash of light. In addition, half of the time a sensor on the participant's arm pulsed (causing a slight tickle) at the exact moment of the tone, and half of the time the sensor did not pulse. The researchers were interested in determining the extent to which these distractions would cause participants to have delayed reaction times to the tone. The researchers measured the amount of time it took participants to press the computer button (in milliseconds). Smaller numbers indicate better performance on the task. Table 12-2 TAELE OF MEANS: ARM TICKLE TICKLE NO TICKLE ROW M Flash of Flash 784.60 627.60 706.10 Light No Flash 547.30 395.50 471.40 COLUMN M 665.95 511.55 $\text { Pop. } M = 588.75$ SOURCE TAELE SOURCE SS df MS F p Flash of Light Arm Tickle 550840.90 1 550840.90 223.79 .000 Light x Tickle 238393.60 1 238393.60 327.72 .000 Residual 67.60 1 67.60 0.02 .884 -What is one independent variable?

When we choose to use nonmanipulated IVs in our factorial experiments, we are conducting ________ research.

Explain in words (using APA-format) the main effect of flash of light.

Describe in words the pattern of results (you do not need to include any statistics).

Suppose you have graphed a significant interaction. The lines on the line graph should

Does there appear to be a main effect of age?

In an ANOVA for mixed samples, why must the between-subjects effects and within-subjects effects be divided in the source table?

Is this a true experiment? Why or why not?

Questions refer to Table 12-1 below. In this study, a researcher is interested in determining if the type of reinforcement affects the number of books read over the summer. A sample of 12-year-old children (half of them boys and half of them girls) is randomly assigned to receive either candy, money, toys, or nothing for every book read over the summer. The mean number of books read over the summer for each group is listed within each cell. Table 12-1: Type of Reinforcement Candy Money Toys None =10 =10 =10 =2 =10 =10 =10 =2 Boys Girls -Consult Table 12-1. This study represents a _________ design.

Which of the following is NOT a consideration for researchers when choosing a particular factorial design?

Is this a two-groups design, a multiple-groups design, or a factorial design? How do you know?

What is the shorthand notation for this experiment? (for example, 2 x 3, 2 x 2 x 2, etc.) Explain your answer.

Example #1: A researcher wishes to examine whether time of day (morning versus afternoon) affects the memory of older and younger participants. He obtains a sample of 40 older individuals and 40 younger individuals and gives them a passage to read. They are later given a test over the passage (scores on the test could range from 0 to 30). Half of the individuals are randomly assigned to read the passage and take the test in the morning, and the other half do so in the afternoon. The data are reported in the table below (the numbers represent mean test scores for each group). Marning Testing Afternoon Testirg Older Adults =15 = Yourger Adults =16 = --Name the other independent variable. a.Is this IV manipulated or not manipulated by the researcher? b.Does this IV represent independent groups or correlated groups? c.How many levels does this IV have?

In a line graph, the presence of an interaction would be indicated by

Describe any deception in this study. What was the purpose of the deception?

Does there appear to be a main effect of time of day? (Note: You are not given any inferential statistics to be able to definitively determine whether there is a main effect. Examine the means and try to determine if they are different or similar to each other).

In a two-variable experiment,

Lola conducts a study to examine aggression. She has both men and women come to a laboratory room that is either 70 degrees or 90 degrees. Suppose she finds that men in a 90-degree room were significantly more aggressive than all other groups. This finding illustrates a(n)

Describe some advantages and disadvantages of using matched pairs/sets, natural pairs/sets, and repeated measures in a factorial design.

Example #3: A researcher wishes to examine whether people high or low in self-esteem react differently to different kinds of therapy for depression. She takes a sample of 120 people (half have high self-esteem and half have low self-esteem) and randomly assigns them to one of three conditions (humanistic therapy, cognitive-behavioral therapy, and a control group of no therapy. She records their level of depression after 3 months of therapy. Scores can range from 1 (very little depression) to 30 (extreme depression). --Name one independent variable. a.Is this IV manipulated or not manipulated by the researcher? b.Does this IV represent independent groups or correlated groups? c.How many levels does this IV have?