Study Designs

Answer

Observational Study Designs

Choosing an appropriate study design is always important in the successful execution of research. While there are many categories of observational designs to choose from, each has its strengths and weaknesses, requiring one to understand the limitations for appropriate study conclusions. Cross-sectional, case control, prospective cohorts and ecological designs are among the main observational studies. This paper aims to elaborate on their strengths and weaknesses and how they optimize either internal or external validity.

Ecological Study Design

The ecological study design is the most basic observational study. The design examines the relationship between outcome and exposure within groups rather than individuals (Thiese, 2014). The ecological study design has its strengths, including less time consuming and easy to use and simple to understand. The design is also inexpensive and examines group data and trends at community or national level. However, the design has coherent weaknesses such as potential misclassifications. There are also difficulties in determining complicated exposure outcome relations under the ecological study design.

Cross-sectional Study Design

The cross-sectional study, which is also referred to as prevalence studies, entails assessing individuals in a study sample, at a given point in time (Thiese, 2014).  Precisely, the study examines relationships between outcomes and exposure prevalences in a given population, at a given point in time. The cross-sectional study design is cost effective, consumes less time and allow simultaneous assessment of multiple outcomes. However, the design has weaknesses that need to be taken into consideration during a study design. For instance, it lacks time elements, hence difficulties in determining relationships between exposures and outcomes.

Case Control Study Design

The case control study design examines various exposures with regards to a given outcome. Fundamentally, researchers identify participants about their case status (Manja & Lakshminrusimha, 2015). The study groups are hence compared to their control counterparts. The study is effective for rare outcomes. Manja and Lakshminrusimha, (2015) identify case control study designs to be effective in assessing multiple exposures. The study is also considered cost effective and less time consuming than the coherent study design.  The case-control study design is, however, difficult in establishing clear chronologies of outcome and exposure. The study design is also biased with regards to study reports.

Prospective Coherent

Prospective coherent study design entails the examination of various health effects of a given exposure. Fundamentally, the study design entails identifying participants concerning their exposure status and assessing them with time to determine their outcomes with regards to the specified outcome of interest (Manja & Lakshminrusimha, 2015).  The study design has various strengths, and thus considered the most effective observation study design. For instance, the study design can evaluate various health outcomes of a single exposure. The design is also efficient for outcomes and exposures with long latency periods. The design can also measure incident directly and establish clear relationships between outcomes and exposure. The coherent study design is, however, costly and time-consuming

Evaluating the Validity of Observational Study Designs

Validity, simply, refers to the lack of systematic errors. Internal validity, therefore, refers to the ability of a study, to cause a difference in the outcome while external validity refers to the ability to generalize the results of a given study to a given population. Cohort and case control study designs can be optimized for external validity due to their ability to generalize results to a universal population (Song & Chung, 2010). Ecological and cross-sectional study designs, on the other hand, can be optimized for internal validity due to their ability to trigger the outcome to study participants.

Overall, the appropriate selection of a study design ensures positive outcomes in a study design. Researchers should, however, take into consideration various aspects such as identification of exposure, access to cases and costs for high validity in their research.