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Different criteria in sampling have to be applied to enhance the effectiveness of a research study. These criteria enable the researcher to ensure that the sample selected for the study is effective in answering the research questions and providing appropriate responses. Some of the sampling criteria necessary in research work for nursing case studies include power analysis for the sample, effective inclusion criteria for the sample, and use of homogenous samples in research.
Power Analysis of the Sample
Power analysis is an essential part of the sampling criteria and allows the researcher to determine the necessary sample size for ensuring statistically accurate findings. It is also essential in determining the effectiveness of the study in detecting the effect of sample size in the study. It is essential because it reduces the likelihood of having sample sizes that are either too large or too small. Sample sizes that are too small reduce precision and effectiveness of the study. Samples that are too big result in wastage of resources without significant addition of efficiency or precision. Proper research design has to ensure that power is reasonably high to enable detection from the null hypothesis. Factors such as sample size, the statistical tests included, and the level of error in experimental measurements may influence the power of the study.
The selected article involved testing the initial effects and feasibility of dietary iron and vitamin C in enhancing nursing home residents' immune status after the administration of an influenza vaccine. The study required the use of old adults from nursing homes, who had to be carefully selected to ensure effectiveness. During the recruitment process, eligible candidates were provided with 30 day iron supplements and measures of their transferrin, iron, hemoglobin, ferritin, influenza A, and influenza B were taken. It was discovered that only the serum transferring levels were different (Crogan, Velasquez, & Gagan, 2005). To ensure that the power of the sample was not compromised, the study had to incorporate aggressive recruitment strategies at multiple sites. It was found that effective results could be achieved by having two groups of three control participants and four treatment participants.
Inclusion criteria are another significant aspect in sampling. They enable the researcher to determine that the subjects selected for inclusion in the sample have all the necessary characteristics. Inclusion criteria are designed based on the research questions being addressed. This ensures the selection of participants who display the expected characteristics and are accessible to the researcher. In this study, the inclusion criteria were comprehensive and increased the ability of the researcher to collect useful data and conduct an effective study.
The inclusion criteria included residents who were 65 years of age or older. The individuals also had to have 1 or more predictors of malnutrition such as weight loss, leaving 25% or more of their food uneaten, psychiatric disorders, and reduced ability to participate in daily activities. Predictors of malnutrition were used in the study because they highlight issues in the efficacy of the vaccine resulting from malnutrition conditions such anemia. The participants were also expected to have resided in a nursing home for 6 months and not having any end stage terminal diagnosis. This is because the study focused on nursing home residents, which means individuals that had not stayed in a nursing home for more than six months would not be representative of the required population. Since the focus of the study was influenza vaccine and the effect of iron supplements, the subjects had to have agreed to get an influenza vaccine and not taking iron supplements at the time (Crogan, Velasquez, & Gagan, 2005). These criteria were meant to ensure that there were no conflicting factors in the test subjects such as supplementation prior to the study or medication for end stage diagnosis.
Homogeneity in the selected samples is a crucial part in the study design utilized in this study. The study design involved having two groups of seven participants each. The two groups were homogenous, but they were exposed to different forms of the intervention to determine variations in outcomes for them. The study used homogenous groups from the different nursing homes in order to assess variations in their health outcomes based on the interventions administered. The first group consisted of seven individuals that were divided into a control group and a treatment group. The control group was not subjected to any interventions, but the control group was given vitamin C and iron supplements with food for thirty days. Residents in both groups had their lab indicators analyzed both before and after the thirty day period. The two treatment groups drawn from the different nursing homes were subjected to different iron supplements.
The first group got 325 mg of ferrous gluconate and the second group 25 mg of chelated iron and 250 mg of vitamin C. In this study, the researchers had to use homogenous groups for the different interventions. This is because it would enable them to assess the effectiveness of the different interventions for without having to address confounding factors resulting from variations in sample characteristics. Comparison of the outcomes for the control and treatment groups would be essential in determining the efficacy of the interventions in increasing immunity resulting from the supplements administered. Initial findings of the study showed that the effect of vitamin C and iron supplements on the immune status was not significant. None of the supplements influenced the level of influenza antibodies with only serum transferrin being significantly different (Crogan, Velasquez, & Gagan, 2005). This comparison was enabled by the homogeneity of the sample selected for the study.