1. Chapter 10 Spotlight on Research- Not All Studies are Experiments- A Nonexper
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1. Chapter 10 Spotlight on Research- Not All Studies are Experiments- A Nonexperiment What kind of milk did you drink as a child: whole milk, 2%, 1%, or skim milk? More precisely, what kind of milk did your parents give you to drink? Presumably, the reduced-fat versions of milk were introduced to promote a healthier diet and reduce the odds of being overweight or obese for children. A recent study examined the relationship between the type of milk consumed and body mass index (BMI) for over 10,000 preschool children at two and four years of age (Scharf, Demmer, & DeBoer, 2013). BMI is a calculated measure of body fat based on height and weight. Although the measure is designed for adults between the ages of 18 and 65, it is reasonably accurate for younger children. The BMI scores are commonly used to classify people into body fat categories: underweight, normal, overweight, and obese. The results of the Scharf et al. study showed that children drinking reduced-fat milk (1% or skim) were more likely to be overweight or obese at age two and age four compared to children drinking whole or 2% milk. In addition, those drinking 1% or skim milk at both age two and age four were more likely to become overweight or obese during the two-year period You may find these results somewhat surprising. Why are children who drink reduced-fat milk more likely to be overweight and obese than children drinking whole or 2% milk? This question arises from a very common, but faulty, assumption. Many people assume that the kind of milk consumed is responsible for each child's weight. Therefore, drinking low-fat milk should produce low-fat children. A more likely explanation, however, is that the child's weight is responsible for the kind of milk that the parents choose to put on the table Specifically, parents are more likely to choose low-fat milk if their children are overweight or obese Because the Scharf et al. study compares groups of scores, it may appear to be another example of experimental research, as was covered in Chapters 7, 8, and 9. Specifically, it strongly resembles the between-subjects experiments presented in Chapter 8. However, note that the Scharf et al. study is missing one or two of the characteristics that are essential for a true experiment. Specifically, there is no manipulated independent variable. Instead, the two groups of participants are defined by the kind of milk they drink, which is not controlled or manipulated by the researchers. In addition, the researchers have no control over the assignment of individuals to groups; a child who drinks reduced-fat milk (1% or skim) automatically goes into the low-fat milk group. without manipulation or control, the study is definitely not an experiment. In fact, this kind of research is known as nonexperimentalExplanation / Answer
1. The correct answer is Option 1. In Scharf's (2013) study, the kind of milk is the nonmanipulated independent variable used to separate children into two groups.
2. The correct answer is Option 1. The researchers cannot be confident that the kind of milk caused changes in the BMI of children because the researchers did not manipulate the kind of milk children drank.
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