Question

An article titled "Guard Your Kids Against Allergies: Get Them a Pet" (San Luis Obispo Tribune, August 28 , 2002) described a study that led researchers to conclude that "babies raised with two or more animals were about half as likely to have allergies by the time they turned six." a. Do you think this study was an observational study or an experiment? Explain. b. Describe a potential confounding variable that illustrates why it is unreasonable to conclude that being raised with two or more animals is the cause of the observed lower allergy rate.

Short answer

a) This study is an observational study because the researchers did not manipulate any variables but only observed the occurrence of allergies in children raised with pets. \ b) A potential confounding variable could be the overall cleanliness and hygiene of the household, or a genetic predisposition to allergies. It's unreasonable to conclude that being raised with two or more animals is the sole cause of the observed lower allergy rate.

Step-by-step solution

Determine the Type of Study

To determine the type of study conducted, consider whether the researchers manipulated any variable or only observed them. It is said that 'babies raised with two or more animals were about half as likely to have allergies by the time they turned six', this suggests that the researchers only observed the occurrence of allergies in children raised with pets, without actually manipulating this variable (e.g., assigning specific pets to specific households). Therefore, this study is an observational study.

Identify a Potential Confounding Variable

To identify a potential confounding variable that could affect the conclusion of the study, consider factors other than 'being raised with two or more animals' that could influence the allergy rate in children. One potential variable could be the overall cleanliness and hygiene of the household. For example, households with pets might enforce stricter cleaning routines which reduce exposure to allergens, leading to a lower rate of allergies. Also, a genetic predisposition to allergies can also be a confounding variable. Therefore, it's unreasonable to conclude that being raised with two or more animals is the sole cause of the observed lower allergy rate.

Key concepts

Confounding Variable

When examining the link between raising children with pets and the prevalence of allergies, it's essential to consider the role of a confounding variable. A confounding variable is an external factor that can influence the observed outcome and mislead researchers to infer a false causal relationship. In the context of the study mentioned, where children raised alongside pets seemingly had a reduced risk of allergies, one major confounding variable could be household income level. Families with higher income might be more likely to own multiple pets and also have better access to healthcare and healthy living environments that could contribute to a lower allergy rate independent of pet ownership.

Another potential confounding variable is parental allergies. If parents have fewer allergies, they may be more inclined to own pets, and their children, due to genetic factors, might also tend to have fewer allergies. This genetic predisposition could skew the correlation, misattributing the allergy prevention to the presence of pets rather than the family's allergy history. Identifying and controlling for such variables is critical in studies to avoid incorrect conclusions.

Causal Relationship

Understanding the nature of a causal relationship is central to interpreting the results of studies like the one described. A causal relationship implies that one event is the result of, or caused by, another—like asserting that exposure to pets directly reduces the likelihood of developing allergies. However, in observational studies, where researchers observe subjects in their natural environment without manipulation, distinguishing causation from mere correlation is challenging.

For example, mere observation cannot rule out the possibility that children who naturally have a robust immune system both tend to have fewer allergies and are more likely to be in environments with pets. To establish a firm causal link, researchers might conduct a randomized controlled trial, where the presence of pets is an assigned variable, not just an observed condition. Until such rigorous experimentation is carried out, any assertion of a causal relationship between pet exposure and allergy prevention remains speculative.

Childhood Allergy Prevention

The topic of childhood allergy prevention is complex and multifaceted, involving environmental, genetic, and lifestyle factors. The hypothesis that exposure to pets might contribute to allergy prevention, known as the 'hygiene hypothesis,' suggests that early exposure to certain microbes helps develop the immune system, reducing the risk of allergies. Nonetheless, this hypothesis is one of many and must be considered within a broader context.

For instance, early introduction to a variety of foods, vitamin D levels, and exposure to farm environments have also been associated with allergy prevention. It is critical for parents and caregivers to be aware that no single factor guarantees allergy prevention and that a combination of good hygiene, balanced diet, and, possibly, pet exposure could play a role. Consulting with pediatricians and allergy specialists is advised for individualized recommendations tailored to each child's health profile and family history.