Quantitative methodological approach are several research designs

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Within the quantitative methodological approach are several research designs. A research
design simply provides more information on how and at what points data will be collected.
The decision of design is driven by the research question and purpose of the study. For
example, if your aim is to measure the effects of psychoeducation on social work clients,
you might take measurements before and after the intervention (pretest-posttest).
Some designs are better than others in terms of validity—the accuracy of the
measurement. For this Discussion, you explore threats to internal validity and determine
which research design is the best at controlling for these threats.
TO PREPARE
Review the Learning Resources on quantitative research.
Consider internal and external validity, the differences between them, and threats to
validity when conducting research.
Reflect on which quantitative research design controls for all threats to internal validity.
Assignment below
Write your initial response to the following:
What is the difference between internal and external validity?
Select two internal validity threats and describe each.
After examining each category and list of designs, determine which design controls for all
threats to internal validity. Explain how this design controls for all threats.

 

 

Sample Solution

Internal vs. External Validity and Research Design

Internal Validity and External Validity are two crucial concepts in research design, particularly quantitative research. They assess different aspects of a study’s trustworthiness:

  • Internal Validity: Refers to the degree of confidence that the observed relationship between variables is causal. In other words, it measures whether the independent variable truly caused the change in the dependent variable, and not some other factor. Threats to internal validity can lead to misleading conclusions about cause and effect.

  • External Validity: Refers to the generalizability of the study’s findings. It indicates whether the results can be applied to a broader population or setting beyond the specific participants and context of the study.

Here are two examples of common internal validity threats:

  1. History: Events that occur between the pretest and posttest (in studies with this design) that could influence the dependent variable. For example, if studying the effectiveness of a new exercise program, participants in both groups might coincidentally join a gym during the study period, affecting their overall fitness.

  2. Selection Bias: Systematic differences between the groups being compared, which could explain the observed results. For example, if studying the effects of meditation on anxiety, participants who volunteer for the meditation group might be inherently less anxious than those assigned to the control group.

No single research design can completely eliminate all threats to internal validity. However, some designs offer greater control than others.

The design that comes closest to controlling for all internal validity threats is the Randomized Controlled Trial (RCT). Here’s how RCTs address the threats mentioned above:

  • History: RCTs randomly assign participants to control and experimental groups. This randomization helps ensure that any events occurring during the study are likely to affect both groups equally, minimizing their impact on the observed results.
  • Selection Bias: Random assignment helps to control for pre-existing differences between groups. Since participants are randomly assigned, any systematic biases are less likely to influence the outcome.

It’s important to note that even RCTs have limitations. For example, they might not be feasible in all situations due to ethical considerations or practical constraints. However, they represent the gold standard for establishing causal relationships and offer the strongest internal validity among quantitative research designs.

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