An observational study in some way can be referred to as a non-guided experiment since it comes from observational or non-experimental studies and its objective is to elucidate cause-and-effect relationships. In an observational study, it is not feasible to use controlled experimentation as one cannot impose the procedures or treatments whose effect is desired to discover. Moreover, it is not possible to assign subjects at random to different processes. Unlike in an experiment, the assignment of treatments to subjects is not controlled by the experimenter, who is supposed to ensure that subjects receiving different treatments are comparable (Song & Chung 2010).
There are three main types of observational studies: cohort studies, case-control studies, and cross-sectional studies (Song & Chung 2010). In cohort studies, a group of people with defined characteristics are followed up to determine the incidence of some specific disease until the disease or outcome of interest occurs. They are advantageous for examining rare exposures since subjects are selected by their exposure status. The case-control study identifies subjects by outcome status at the outset of the investigation and in comparison to the case-control study it allows for multiple exposures or risk factors to be assessed for one outcome. A cross-sectional study looks at the prevalence of disease and exposure at one moment in time. Unlike a cohort study, a cross-sectional study begins by selecting a sample population and then the data are obtained to classify all individuals in the sample as either having or not having the health outcome.
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The three observational studies have several advantages. According to Song & Chung, cohort study gathers data regarding a sequence of events which means it can assess causality. A case-control study is advantageous as it’s good for examining rare outcomes or outcomes with long latency and it is relatively inexpensive. Finally, the advantage of a cross-sectional study is it can be used to prove and disprove assumptions (2010). As stated by Song & Chung the observational studies have disadvantages because cohort studies require large numbers of subjects to study rare exposures. A case-control study, on the other hand, is susceptible to recall bias or information bias. Additionally, a cross-section study cannot be used to analyze behavior over a period (2010).
An example of useful observational study is research on long-term psychological effects of the death of a close relative. For instance, if a study is carried out to estimate the psychological effects of the death of a close relative, and data is collected following the sudden death of a spouse or a child in a car crash. After an analysis is carried out and the study concludes that both spouses and parents show clear evidence of depression and lack of resolution during the time of the interview. The study is considered to be useful since it follows clear guidelines. An example of misleading research is an attempt to compare the effect of smoking on heart conditions in a group of participants. Males are more likely to suffer a heart condition, and at the same time, they are more likely to smoke making the study misleading. A better study is to separate the group into males or females then establish a control from each of the separate groups.
Interpreting and understanding mainstream research can also be challenging. Unlike in an experimental study, the investigator in an observational study can only observe the effects of an exposure on the study subjects which means he or she does not play any role in assigning exposure to the study subjects (Song & Chung 2010). This makes observational studies vulnerable to methodological problems. Since the study is based on observation there needs to be a good review of how the data fields are lined up; a researcher needs first to thoroughly check the source of data since some sources of mainstream data tweak their polling to catch the audience's attention. The misleading information may lead the audience in believing one data is above the other by changing their figures.
Since observational studies are based on the researcher’s observation and interpretation, the results of an observational study are wholly dependent on the ethics of the researcher and how well the preparations are carried out. Observational studies, therefore, must be put under scrutiny to determine if they were carried out according to proper scientific guidelines. The ethical issues involved in observational studies make them not easy to trust unless determined otherwise.
References
Song, J. W., & Chung, K. C. (2010). Observational studies: cohort and case-control studies. Plastic and reconstructive surgery, 126(6), 2234.
Rosenbaum, P. R. (2002). Observational studies. In Observational studies (pp. 1-17). Springer, New York, NY.
