Upon critically analysing the case control study, it can be said that that the study was extremely susceptible to selection bias. The initial hint that selection bias might be present is the manner in which the researchers selected their participants. Being a case control, and hence very susceptible to such bias, a target population should have been designated prior to selecting the subjects. In this particular study the cases were selected from Kellyaniawhich has been previously mentioned to be primarily rural in geography whilst the control group was selected from the city of Schlubville. This would mean that the control group might not be representative of the Kelyania population. It would have been more appropriate to select both the cases and controls from Kelyania as a whole. This susceptibility to selection bias is further complemented by the mere fact that the study itself is a case control. Thus, the researchers were limited by the subjects they were capable of picking from the onset.
Additionally, there is a clear low response rate from the controlled group. If the participants which suffered from motor-neurone disease (cases) were more willing to participate when compared to the those which did not (controls), randomization might have been compromised and consequently leading to selection bias (The sample is not reflective of the entire population).
Another noteworthy finding is the fact that the population selected as the control was 10.2 years younger than those who chose not to participate. Furthermore, it is mentioned that younger individuals were more likely to swim that older ones. This is worrisome as the sample of controlled subjects might not represent the actual exposure prevalence of Schlubville as a whole thus contributing even more to the possibility of selection bias. Finally, the mere fact the control subjects were selected from urban areas might allude to a healthier sample which is less likely to develop MND than the case subjects which were dispersed across Kellyania. This could be viewed as a form of the healthy worker effect. The aetiology of MND is not well identified, however there is speculation that viruses, or even toxins might be involved in the natural history of the disease (add references). Therefore, people in an urban environment might be less exposed to such risk factors and thus less likely to develop the disease. This must be factored in when considering selection bias.
Although various weaknesses in the study have been identified in relation to selection bias, a certain amount of strengths were detected as well. The first strength of the study includes the random selection of cases in the control group. However, the random selection of the controlled group was extracted from an unspecified electoral roll in Schlubville. Information regarding the electoral roll was thus not provided. This is essential for the assessment of selection bias, and it provides us with a well-defined target population. In fact, numerous factors associated with the electoral roll could influence the representation of the controlled group. Questions that could arise include: “From which year was the electoral roll?”; “Was it an national electoral roll or for a local government?”; “Is voting mandatory in Kellyania?”; “Does everyone has the right to vote in Kellyania?”. Specifics one time, and characteristics of the sample were not discussed. In other words, how representative is the electoral roll of Schlubville, and more importantly, Kellyania population. All these outcomes could influence the representation of the control group. The second strength was the use of invitations to retrieve participants, instead of attracting volunteers. Volunteers could have a common specified trait that instigates them to join a particular study. This trait could therefore could influence the type of subjects the researchers would obtain and in doing would prevent them from obtaining a sample which is representative of Kellyanias population. Thus, their approach in selecting the subjects is an appropriate method which attempts to limit selection bias.
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Upon critically analysing the case control study, it can be said that that the study was extremely susceptible to selection bias. The initial hint that selection bias might be present is the manner in which the researchers selected their participants. Being a case control, and hence very susceptible to such bias, a target population should have been designated prior to selecting the subjects. In this particular study the cases were selected from Kellyaniawhich has been previously mentioned to be primarily rural in geography whilst the control group was selected from the city of Schlubville. This would mean that the control group might not be representative of the Kelyania population. It would have been more appropriate to select both the cases and controls from Kelyania as a whole. This susceptibility to selection bias is further complemented by the mere fact that the study itself is a case control. Thus, the researchers were limited by the subjects they were capable of picking from the onset.
Additionally, there is a clear low response rate from the controlled group. If the participants which suffered from motor-neurone disease (cases) were more willing to participate when compared to the those which did not (controls), randomization might have been compromised and consequently leading to selection bias (The sample is not reflective of the entire population).
Another noteworthy finding is the fact that the population selected as the control was 10.2 years younger than those who chose not to participate. Furthermore, it is mentioned that younger individuals were more likely to swim that older ones. This is worrisome as the sample of controlled subjects might not represent the actual exposure prevalence of Schlubville as a whole thus contributing even more to the possibility of selection bias. Finally, the mere fact the control subjects were selected from urban areas might allude to a healthier sample which is less likely to develop MND than the case subjects which were dispersed across Kellyania. This could be viewed as a form of the healthy worker effect. The aetiology of MND is not well identified, however there is speculation that viruses, or even toxins might be involved in the natural history of the disease (add references). Therefore, people in an urban environment might be less exposed to such risk factors and thus less likely to develop the disease. This must be factored in when considering selection bias.
Although various weaknesses in the study have been identified in relation to selection bias, a certain amount of strengths were detected as well. The first strength of the study includes the random selection of cases in the control group. However, the random selection of the controlled group was extracted from an unspecified electoral roll in Schlubville. Information regarding the electoral roll was thus not provided. This is essential for the assessment of selection bias, and it provides us with a well-defined target population. In fact, numerous factors associated with the electoral roll could influence the representation of the controlled group. Questions that could arise include: “From which year was the electoral roll?”; “Was it an national electoral roll or for a local government?”; “Is voting mandatory in Kellyania?”; “Does everyone has the right to vote in Kellyania?”. Specifics one time, and characteristics of the sample were not discussed. In other words, how representative is the electoral roll of Schlubville, and more importantly, Kellyania population. All these outcomes could influence the representation of the control group. The second strength was the use of invitations to retrieve participants, instead of attracting volunteers. Volunteers could have a common specified trait that instigates them to join a particular study. This trait could therefore could influence the type of subjects the researchers would obtain and in doing would prevent them from obtaining a sample which is representative of Kellyanias population. Thus, their approach in selecting the subjects is an appropriate method which attempts to limit selection bias.
TAKE ADVANTAGE OF OUR PROMOTIONAL DISCOUNT DISPLAYED ON THE WEBSITE AND GET A DISCOUNT FOR YOUR PAPER NOW!