Cross-Sectional, Case-Control and Cohort Studies
Name
Institutional Affiliation
Question One
Cross-sectional studies are researches analyzing prevalence. This means that the researcher investigates certain outcomes by collecting data from a sample population at a given time. With this type of research, varying population groups are compared to the lowest etiology hierarchy level. Its purpose is to determine the prevailing population characteristics of a population. Potential bias can arise from participants who are non-responders.
The purpose of case-control studies is to determine whether exposure is linked to an outcome. They entail comparing patients who have certain characteristics such as diseases or interest outcomes to the ones without. The participants with the outcome of interest are referred to as cases, while those being compared are known as control subjects (Liu, 2019). These studies have level four of evidence just like the cohort and offer stronger association measures of causality than cross-sectional. Potential bias could be in the selection of participants.
Cohort studies are utilized for studying causes, incidences, and prognosis (Liu, 2019). Their purpose is to examine disease causes and establish the association of health outcomes and risk factors. They analyze events in sequential order and are suitable for distinguishing cause and effect. There is a potential selection bias because of the lack of follow-up of the participants.
Question Two
For controlled studies, participants are selected randomly from a sample group rather than referencing the whole population. The pros of controlled studies include statistical reliability, minimum bias, comparison value, and the fact that they are publishable. The limitation is that the result may not mimic real-life situations. The ethical challenges include risk minimization, informed consent, and confidentiality. Validity can be improved by adding placebo groups.
Since quasi-experimental studies entail manipulating participants from an independent variable, participants’ selection criteria will involve similar participants to be divided into two. The pro is that these studies are affordable since they need fewer resources (Borusyak et al., 2018). The disadvantage is the potential confounding bias that may promote drawing wrong causal inferences. The ethical challenges include privacy and confidentiality. Validity can be ensured during selection by increasing randomization and blinding the experiments.
Question Three
https://www.sciencedirect.com/science/article/abs/pii/S0140673618308419
The research question is assessing the prevalence and main risk factors of COPD in China. The research is a cross-sectional study design with 2015779 adults from all over china aged 20 years and above (Wang et al., 2018). Al participants had to be tested for the disease and were randomly assembled from various provinces in China. The only variable was the presence of COPD tested on those who had reliable post-bronchodilator test results.
The study results showed a high prevalence of COPD among the adult population in China, with the primary risk factors including smoking, low education, and air pollution. Therefore, early detection and prevention should be a priority using spirometry to reduce mortality. The observed ethical issue was informed consent. The potential bias arose from potential non-respondents.
Question Four
I would re-phrase the question to meet my current research needs. The study question would be investigating the urban and countryside variations when it comes to COPD prevalence. I would not change the participants because they were randomly selected from provinces all around the country. I would change the variables to rural and urban participants. The variables will be measured using survey questions and a lung function test.
The selection criteria will be random, with participants both from rural and urban setups. The potential ethical issues to encounter would be risk minimization, informed consent, and confidentiality. I would minimize the bias of non-respondents by providing the participants with informed consent.
Reference
Borusyak, K., Hull, P., & Jaravel, X. (2018). Quasi-experimental shift-share research designs (No. w24997). National Bureau of Economic Research.
Liu, H. (2019). Analyzing the Relationship between Cohort and Case-Control Study Results Based on Model for Multiple Pathogenic Factors. Computational and Mathematical Methods in Medicine, 2019.
Wang, C., Xu, J., Yang, L., Xu, Y., Zhang, X., Bai, C., … & China Pulmonary Health Study Group. (2018). Prevalence and risk factors of chronic obstructive pulmonary disease in China (the China Pulmonary Health [CPH] study): a national cross-sectional study. The Lancet, 391(10131), 1706-1717.