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Researchers at the University of Utah carried out a study to see if the size of the fork used to eat dinner has an effect on how much food is consumed (Food Network Magazine, January 2012). The researchers assigned people to one of two groups. One group ate dinner using a small fork, and the other group ate using a large fork. The researchers found that those who ate with a large fork ate less of the food on the plate than those who ate with the small fork. The title of the article describing this study was "Dieters Should Use a Big Fork." This title implies a cause-and-effect relationship between fork size and amount eaten and also generalizes this finding to the population of dieters. What would you need to know about the study design to determine if the conclusions implied by the headline are reasonable?

Short Answer

Expert verified
To determine if the conclusions implied by the headline are reasonable, we need to analyze the study design, identify the target population, control for confounding factors, understand the methodology for measuring food consumption, and assess statistical significance. This analysis will help us evaluate the cause-and-effect relationship between fork size and food consumption and the generalization of findings to the population of dieters.

Step by step solution

01

Analyze the study design

First, we need to know about the design of the study. Was it a random controlled trial (RCT), observational study, or any other type of study? A well-designed RCT has the potential to show a cause-and-effect relationship, while an observational study can only demonstrate an association. We should also know the sample size used in the study, as larger sample sizes allow for more robust conclusions.
02

Identify the study population

Next, we need to determine the target population of the study. Were the participants dieters or just random people, as it generalizes the finding to the population of dieters? Understanding the study population will help us evaluate if the results are applicable to dieters or not.
03

Confirm the control over confounding factors

It is crucial to know if the study controlled for potential confounding factors that could influence the amount of food eaten, such as the participants' hunger, type of food served, portions, or the participants' awareness of the study. A properly controlled study takes into account these influences and isolates the effect of fork size on food consumption.
04

Understand the methodology of measuring food consumption

We need to know how the researchers measured the amount of food consumed. Was it self-reported or objectively measured? Was it measured in grams, calories, or another unit? Ensuring accurate and consistent measurements is vital to validate the conclusions about the cause-and-effect relationship between fork size and food consumption.
05

Assess statistical significance

Finally, we need to know if the differences in food consumption between the two groups were statistically significant. Did the analysis include confidence intervals or p-values, and were they large enough to indicate a real effect? This information will help us determine if the study's conclusions are truly statistically significant or if the findings might be due to chance. By analyzing the study design, identifying the study population, evaluating control over confounding factors, understanding the measurement methodology, and assessing statistical significance, we can determine if the conclusions implied by the headline "Dieters Should Use a Big Fork" are reasonable and applicable to the population of dieters.

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Key Concepts

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

Random Controlled Trial
The essence of a random controlled trial (RCT) is to draw reliable conclusions about cause-and-effect relationships. In RCTs, participants are randomly assigned to either the experimental group or the control group. This randomization minimizes the biases and ensures that both groups are similar in all respects except for the intervention being tested—in this case, fork size. When considering the University of Utah study, we would look for details indicating that the assignment to small or large fork groups was indeed random. Such a methodological foundation strengthens the argument that differences in food consumption can be attributed specifically to fork size rather than other variables.
Study Population Relevance
The relevance of study population in research cannot be overstated—knowing who the participants are helps us understand how generalizable the results are. Since the study claims findings pertinent to dieters, we must confirm whether all participants were indeed dieters or if the study extended to a broader demographic. Knowing this allows us to evaluate if the tagline 'Dieters Should Use a Big Fork' is founded on relevant evidence. It's crucial too to consider demographic diversity among participants, such as age, gender, dieting behavior, and cultural eating habits, to ensure the results are not skewed by a particular subgroup within the study.
Control of Confounding Factors
Controlling confounding factors means identifying and minimizing variables that could influence the outcome of the study other than the variable of interest. In the fork size study, factors such as the type of meal, portion sizes, the participants’ hunger level, and even the dining setting could affect food consumption. These confounders should be either kept constant or measured and adjusted for in the analysis. By controlling these factors, the researchers can isolate the effect of fork size on food consumption and assure that the conclusions drawn are valid. If the study accounts for these potential confounders, it means the researchers have made efforts to avoid misleading results.
Measurement Methodology
In any study, how data is collected—the measurement methodology—directly impacts the reliability of the conclusions. For the fork size study, we would inquire about the specifics of how food consumption was measured. Was there a standard protocol to measure the amount of food left on the plate accurately? Did the methodology involve weighing the leftovers or using a more subjective scale? The selection of measurement tools determines the precision of the results; hence, it's paramount that the approach is as objective and standardized as possible to avoid measurement error and to provide a solid basis for comparison between different group outcomes.
Statistical Significance
Statistical significance is a measure of whether the results of the study are likely to be due to chance or if they reflect a true effect. To assess this, the study would need to provide p-values or confidence intervals, with smaller p-values (typically less than 0.05) indicating less likelihood that the observed effects are due to chance. A scientifically rigorous study would demonstrate sufficient statistical power, often through larger sample sizes, to detect a meaningful difference if one exists. Understanding these statistics helps determine whether the 'big fork' effect is compelling enough to recommend as a dieting strategy.

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Most popular questions from this chapter

"Should You Get a Flu Shot? Your Physical and Financial Health Is on the Line" is the title of an article that appears in a blog on the WalletHub web site (December 20 , 2013, wallethub.com/blog/flu-shot-survey/1303/, retrieved September 25,2016 ). The author reported that an infectious disease expert from a top medical school in each of the 50 states was asked if he or she would recommend that the average person get a flu shot. Based on the 50 responses, it was reported that \(94 \%\) would recommend a flu shot. a. Suppose that the purpose of this survey was to estimate the percentage of all doctors who would recommend a flu shot. Would this sample be a simple random sample, a stratified sample, a systematic sample, or a convenience sample? Explain. b. Explain why an estimate of the percentage who would recommend a flu shot that was based on data from this sample should not be generalized to all doctors.

Use the following information to answer Exercise. Many surgeons play music in the operating room. Does the type of music played have an effect on the surgeons' performance? The report "Death Metal in the Operating Room" (NPR, December 24, 2009, www.npr.org, retrieved April 8,2017 ) describes an experiment in which surgeons used a simulator to perform a surgery. Some of the surgeons listened to music with vocal elements while performing the surgery, and others listened to music that did not have vocal elements. The researchers concluded that the average time to complete the surgery was greater when music with vocal elements is played than when music without vocal elements is played. Could the experiment described above have been double-blind? Explain why or why not.

The supervisors of a rural county are interested in the proportion of property owners who support the construction of a sewer system. Because it is too costly to contact all 7000 property owners, a survey of 500 owners (selected at random) is undertaken. Describe the population and the sample for this problem.

For each of the following, determine whether the statistical study described is an observational study or an experiment. Give a brief explanation of your choice. a. Can choosing the right music make wine taste better? This question was investigated by a researcher at a university in Edinburgh (www.decanter.com/wine-news /montes-music-makes-wine-reach-parts-it-otherwise -couldnt-reach-82325/, retrieved April 8,2017 ). Each of 250 volunteers was assigned at random to one of five rooms where they were asked to taste and rate a glass of wine. No music was playing in one of the rooms, and a different style of music was playing in each of the other four rooms. The researcher concludedFor each of the following, determine whether the statistical study described is an observational study or an experiment. Give a brief explanation of your choice. a. Can choosing the right music make wine taste better? This question was investigated by a researcher at a university in Edinburgh (www.decanter.com/wine-news /montes-music-makes-wine-reach-parts-it-otherwise -couldnt-reach-82325/, retrieved April 8,2017 ). Each of 250 volunteers was assigned at random to one of five rooms where they were asked to taste and rate a glass of wine. No music was playing in one of the rooms, and a different style of music was playing in each of the other four rooms. The researcher concluded that cabernet sauvignon is rated more highly when bold music is played than when no music is played. b. The article "Display of Health Risk Behaviors on MySpace by Adolescents" (Archives of Pediatrics and Adolescent Medicine [2009]: 27-34) described a study of 500 publically accessible MySpace web profiles posted by 18 -year- olds. The content of each profile was analyzed and the researchers concluded that those who indicated involvement in sports or a hobby were less likely to have references to risky behavior (such as sexual references or references to substance abuse or violence). c. USA TODAY (January 29,2003 ) reported that in a study of affluent Americans (defined as those with incomes of \$ 75,000\( or more per year) \)57 \%$ indicated that they would rather have more time than more money. d. The article "Acupuncture for Bad Backs: Even Sham Therapy Works" (Time, May 12,2009 ) summarized a study conducted by researchers at the Group Health Center for Health Studies in Seattle. In this study, 638 adults with back pain were randomly assigned to one of four groups. People in group 1 received the usual care for back pain. People in group 2 received acupuncture at a set of points tailored specifically for each individual. People in group 3 received acupuncture at a standard set of points typically used in the treatment of back pain. Those in group 4 received fake acupuncture- they were poked with a toothpick at the same set of points used for the people in group 3 . Two notable conclusions from the study were: (1) patients receiving real or fake acupuncture experienced a greater reduction in pain than those receiving usual care; and (2) there was no significant difference in pain reduction between those who received real acupuncture (groups 2 and 3 ) and those who received fake acupuncture toothpick pokes.

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