When designing any study in epidemiology, it is crucial to ensure that an adequate sampling plan has been created. Without an appropriate sampling of the target population, the study will lack validity. In this study, a sample will be utilized to examine the correlation between childhood obesity and early onset diabetes. Obesity is a well-known risk factor for the development of diabetes. However, as the incidence of childhood obesity increases at significant rates, it is important to further examine the impact of childhood obesity. Specifically, it is crucial to gain a better understanding of the risk childhood obesity plays in the development of early onset diabetes.
In epidemiology, a target population refers to the group or population that the findings should relate to overall. In other words, if the study indicates that A is a causation of B in the sample, ideally, this should be true for the entire population to which the study refers (Oleckno, 2002, pp. 84-85). In this study, the target population will be children suffering from childhood obesity. The goal of the study will be to determine if this target population suffers from an increased risk of developing early onset diabetes. The purpose will be to examine if childhood obesity is a risk factor for the outcome of early onset diabetes.
It is important to define childhood obesity in order to correctly establish a proper target population. In health care, obesity has specific guidelines. This is different than how the general population may view obesity. The Centers for Disease Control and Prevention (CDC) also has specific guidelines to identify childhood obesity. Since children grow rapidly, overweight and obesity is defined relative to the percentile for the age and sex of the child.
The CDC utilizes Body Mass Index (BMI) to determine the child’s percentile. BMI is properly calculated by an individual’s height and weight. According to the CDC, a child is considered overweight if the BMI is at or above the 85th percentile, but lowers than the 95th percentile for children of the same age and sex. A child is considered obese is his or her BMI is at or above the 95th percentile for a child of the same age and sex (CDC, 2012).
Since this study will examine childhood obesity, the children selected to participate will have to fall in the 95th or greater percentile of other children of the same age and sex. Obviously, this limits the number of children who may participate; if the study examined overweight children, there would be more children from which the sample could be generated. However, even with the 95th or greater percentile, sadly, it will leave a significant amount of individuals who are eligible. As of 2010, according to the CDC, 14.94% of children were classified as obese. The prevalence of extreme obesity in children was 2.07% (CDC, 2012).
In epidemiology and statistics, a sampling frame refers to “a list or other device used to define a researcher’s population of interest. The sampling frame defines a set of elements from which a researcher can select a sample of the target population” (Currivan, 2004). Sampling frames are utilized because a researcher cannot study the entire population of individuals with relation to a condition. For instance, it would be impossible to allow all children who are classified as obese to participate in the study. The time and cost of this practice is prohibitive. As a result, sampling is used to represent the population. In this case, the sampling frame would involve children who are at or above the 95th percentile in weight for their age and sex.
The sample refers to a subset of the target population. The sample tends to be better defined than the population because of its smaller size. In this study, a sample would consist of all the children chosen to participate in the study; these children would need to meet the parameters defined by the sampling frame. On average, the larger the sample size, the greater power the study will have. However, it is also important to choose a sample of a reasonable size. Larger samples are more difficult to track and more costly overall (Blair & Taylor, 2008, pp. 2-4).
The recruitment strategy will consist of seeking out children who meet these criteria through a variety of methods. Flyers requesting subjects can be posted at a number of large pediatric services. They can also be posted at local public health centers. Unfortunately, children from lower socioeconomic groups are more likely to suffer from obesity. Since many of these children utilize government health insurance, public health centers will be an ideal location to recruit the study participants. It is important that the study be discrete and upholds all ethical standards. In today’s world, bullying is a common occurrence among children. Children who suffer from childhood obesity or are overweight are more likely to be bullied. Therefore, all protections for these children must be ensured, both during the recruitment period and during the study. For this reason, posting the study ads in the private exam rooms may enable parents to access the information in a more discrete method. It is obviously crucial to obtain permission from the pediatric services as well as the public health department before utilizing these methods. Since these groups will be stakeholders in the study, it is important to ask them for input regarding the recruitment strategies. As primary care providers of children with weight problems, they likely will have excellent ideas concerning the protection of the study participants.
When designing a study, it is crucial to clearly establish the criteria for several groups related to it. These groups include the target population, the sampling frame and the sample. Additionally, it is important to determine a recruitment strategy that is ethical and ensures the protection of all potential participants. These are not items that can be addressed after the sample has been determined. These are items that must be thoroughly considered and discussed prior to the use of any recruitment strategy.
- Blair, RC., & Taylor, RA. (2008). Biostatistics for the health sciences. Upper Saddle River: Pearson Prentice Hall.
- CDC. (2012, April 27). Basics about childhood obesity. Retrieved October 18, 2013, from: http://www.cdc.gov/obesity/childhood/basics.html
- Currivan, DB. (2004). Sampling frame. SAGE Research Methods. Retrieved October 18, 2013, from: http://srmo.sagepub.com/view/the-sage-encyclopedia-of-social-science-research-methods/n884.xml
- Oleckno, WA. (2002). Essential epidemiology. Long Grove: Wakeland Press.