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Chapter 1: Problem 3

For each of the statistical studies described indicate whether the study is an observational study or an experiment. Give a brief explanation for your choice. An article in USA Today (October 19,2010 ) describes a study of how young children learn. Sixty-four 18 -month-old toddlers participated in the study. The toddlers were allowed to play in a lab equipped with toys, which also had a robot hidden behind a screen. The article states: "After allowing the infants play time, the team removed the screen and let the children see the robot. In some tests, an adult talked to the robot and played with it. In others the adult ignored the robot. After the adult left the room, the robot beeped and then turned its head to look at a toy to the side of the infant. In cases where the adult had played with the robot, the infant was four times more likely to follow the robot's gaze to the toy."

Short Answer

Expert verified
The statistical study described in the exercise is an Experiment because the researchers intentionally controlled variables such as the interaction between adult and robot, as well as the robot's actions, and then observed the effect on the toddlers' responses.

Step by step solution

01

Identify the Role of Researchers

In the study, the researchers allow the toddlers to play in a lab with toys and present a robot with a different set of actions. It means they are controlling the variables, deciding which toddlers see an adult interacting with the robot, and which ones see an adult ignoring it.
02

Identify the Manipulation of Variables

The researchers alter the environment by controlling the robot's activity and adult's interaction with it, then observe the toddler's reaction. This shows there is an intentional change in conditions.
03

Classify the Type of Study

Since researchers manipulate the variables and measure the effect, which in this case is the toddler's reaction to robot's gaze, this study falls under experimental studies. Experimental studies involve manipulation of one variable to determine if changes in one variable lead changes in another variable.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Observational Study
In an observational study, researchers collect data without interfering with the subjects' environment or behavior. They observe and record findings as they unfold naturally. Unlike experiments, they do not manipulate variables and therefore cannot establish causal relationships as confidently.

For instance, if we were to just observe the toddlers' interactions with toys and the robot without any induced conditions, that would constitute an observational study. Researchers would note how often, if at all, toddlers looked where the robot was looking, but wouldn't influence their behavior by introducing an adult into the scenario.
Manipulation of Variables
The manipulation of variables is a defining feature of experimental studies. Here, the researchers actively change one or more variables to observe the effect of these changes on other variables. In the toy and robot study, manipulation occurs when an adult either interacts with the robot or ignores it.

The toddlers' subsequent reaction to the robot's actions is observed to see how the manipulated variable, which is the presence and behavior of the adult, influenced the toddlers' gaze following behavior.
Control Group
A control group is pivotal in experimental research design. It's a baseline group that does not receive the experimental manipulation. This group helps researchers compare results and understand the effects of the manipulated variable.

In the context of our robot study, if some toddlers watched a robot without having seen any adult-robot interaction (assuming this scenario is common in their daily experience), that group of toddlers could be viewed as a control group against which to compare the behavior of toddlers who observed the adult playing with the robot.
Dependent and Independent Variables
An independent variable is the one that researchers manipulate, while the dependent variable is the outcome they are interested in measuring.

In the discussed study, the independent variable could be the adult's interaction with the robot (since this is manipulated). The dependent variable would be the toddler's likelihood of looking at the toy that the robot gazed at after beeping. This relationship demonstrates the effect of the former on the latter and allows researchers to make conclusions about cause and effect within the experiment.

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Most popular questions from this chapter

The paper "From Dr. Kildare to Grey's Anatomy" (Annals of Emergency Medicine [2010]: \(21 \mathrm{~A}-23 \mathrm{~A}\) ) describes several studies of how the way in which doctors are portrayed on television might influence public perception of doctors. One study was described as follows: Rebecca Chory, Ph.D., now an associate professor of communication at West Virginia University, began studying the effect of such portrayals on patients' attitudes toward physicians. Using a survey of 300 undergraduate students, she compared perceptions of physicians in 1992 - the end of the era when physicians were shown as all-knowing, wise father figures-with those in \(1999,\) when shows such as \(E R\) and Chicago Hope \((1994-2000)\) were continuing the transformation to showing the private side and lives of physicians, including vivid demonstrations of their weaknesses and insecurities. Dr. Chory found that, regardless of the respondents' personal experience with physicians, those who watched certain kinds of television had declining perceptions of physicians' composure and regard for others. Her results indicated that the more prime time physician shows that people watched in which physicians were the main characters, the more uncaring, cold, and unfriendly the respondents thought physicians were. a. Answer the following four questions for the observational study described in this exercise. (Hint: Reviewing Examples 1.3 and 1.4 might be helpful.) 1\. What is the population of interest? 2\. Was the sample selected in a reasonable way? 3\. Is the sample likely to be representative of the population of interest? 4\. Are there any obvious sources of bias? b. Based on the study design, do you think that the stated conclusions are reasonable?

The Institute of Psychiatry at Kings College London found that dealing with "infomania" has a temporary, but significant, negative effect on IQ (Discover, November 2005). To reach this conclusion, researchers divided volunteers into two groups. Each subject took an IQ test. One group had to check e-mail and respond to instant messages while taking the test, and the other group took the test without any distraction. The distracted group had an average score that was 10 points lower than the average for the control group. Explain why it is important that the researchers use random assignment to create the two experimental groups.

A New York psychologist recommends that if you feel the need to check your e-mail in the middle of a movie or if you sleep with your cell phone next to your bed, it might be time to "power off' (AARP Bulletin, September 2010). Suppose that you want to learn about the proportion of students at your college who feel the need to check e-mail during the middle of a movie, and that you have access to a list of all students enrolled at your college. Describe how you would use this list to select a simple random sample of 100 students.

Is doing tai chi, a traditional Chinese martial art, good for the immune system? The authors of a paper that appeared in the Journal of the American Medical Association (2007, pages 511-517) describe an experiment in which 112 healthy older adults were assigned at random to one of two groups. One group was the tai chi group. People in this group did tai chi for 40 minutes, three times a week, for 16 weeks. At the end of the 16 weeks, they received a vaccine designed to protect against a certain virus. Nine weeks later, a measurement of immunity to the virus was made. People in the second group served as a control group. They did not do tai chi during the first 16 weeks but received the virus vaccine at the same time as the tai chi group, and their immunity was also measured nine weeks later. a. Briefly describe why it was important for the researchers to assign participants to one of the two groups rather than letting the participants choose which group they wanted to be in. b. Explain why it was important to include a control group in this experiment.

In 2000 , the chairman of a California ballot initiative campaign to add "none of the above" to the list of ballot options in all candidate races was quite critical of a Field poll that showed his measure trailing by 10 percentage points. The poll was based on a random sample of 1,000 registered voters in California. He is quoted by the Associated Press (January 30,2000 ) as saying, "Field's sample in that poll equates to one out of 17,505 voters." This was so dishonest, he added, that Field should get out of the polling business! If you worked on the Field poll, how would you respond to this criticism?
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