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Refer to a clinical study conducted at the Houston Veterans Administration Medical Center on the effectiveness of knee surgery to cure degenerative arthritis (osteoarthritis) of the knee. Of the 324 individuals who met the inclusion criteria for the study, 144 declined to participate. The researchers randomly divided the remaining 180 subjects into three groups: One group received a type of arthroscopic knee surgery called debridement; a second group received a type of arthroscopic knee surgery called lavage; and a third group received skin incisions to make it look like they had had arthroscopic knee surgery, but no actual surgery was performed. The patients in the study did not know which group they were in and in particular did not know if they were receiving the real surgery or simulated surgery. All the patients who participated in the study were evaluated for two years after the procedure. In the two-year follow-up, all three groups said that they had slightly less pain and better knee movement, but the "fake" surgery group often reported the best results. (a) Describe as specifically as you can the target population for this study. (b) Describe the sample.

Step by step solution

01

Identify the Target Population

From the information provided, the target population for this study would be all individuals with degenerative arthritis (osteoarthritis) of the knee who met the inclusion criteria for the study. This population is of interest for the investigators as they want to test the effectiveness of knee surgery to cure this specific type of arthritis.

02

Identify the Sample

The sample of this study consists of the selected participants from the target population who agreed to participate. Initially, there were 324 individuals who met the inclusion criteria, but 144 declined to participate. Therefore, the sample of this study is the remaining 180 individuals who did opt to participate. The researchers divide this sample further into three groups for the study.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Target Population

In clinical study design, defining the target population is a crucial first step. It determines whom the study results will apply to and helps narrow down the research scope. In this case, the target population includes individuals with degenerative arthritis (osteoarthritis) of the knee who meet specific inclusion criteria. These criteria are usually established to ensure that the participants' characteristics align closely with the study goals.
Understanding the target population allows researchers to generalize findings beyond the study sample, providing insights into how effective treatments might be for a broader group.
Researchers must carefully define and clearly document the characteristics of the target population to ensure the study's integrity and relevance.

• Inclusion Criteria: These are the specific traits or conditions that participants must have to be part of the study.
• Exclusion Criteria: Conversely, these are characteristics that disqualify potential participants to maintain data integrity and validity.

Effective clinical research relies heavily on how well the target population is defined, as this can significantly impact the reliability and applicability of the study outcomes.

Sampling Method

The sampling method employed in a study determines the validity of its results. It's essentially how researchers select participants from the target population. Often, a study can't include everyone, so a sample is taken. For the clinical study discussed, out of 324 individuals who met the criteria, a smaller group of 180 individuals formed the sample.
Random selection is a preferred method in clinical studies because it minimizes biases. In the Houston study, researchers used random sampling to decide which of the 180 subjects were placed into each experimental group, ensuring each participant had an equal chance of selection.

• Random Sampling: Helps create a representative sample by giving each member of the population an equal chance of being included.
• Sample Size: It's critical to determine an appropriate number of participants to balance research accuracy with resource constraints.

Random sampling ensures fairness and helps in achieving a data set that accurately reflects the diversity within the target population.

Experimental Groups

In clinical trials, creating experimental groups is essential for comparing different treatments and their effects. The Houston study efficiently divided the sample of 180 participants into three groups to examine the outcomes of different surgical procedures.
Each group received a varied intervention: one was given debridement, another lavage, and a third received the simulation of surgery, acting as a control group.
This setup allows researchers to control variables and draw reliable conclusions about which treatment, if any, is most effective. Blinding participants ensured unbiased feedback as the "fake" surgery group's reaction could be compared against the real ones.

• Control Group: This group is crucial as it doesn't receive the experimental treatment but is handled similarly otherwise. It allows researchers to measure the treatment's effect against no active intervention.
• Treatment Group: Groups receiving the actual interventions being tested.

The design of experimental groups is vital for extracting authentic results, allowing researchers to deduce or discount the placebo effect observed in clinical trials.