What must be ensured in an experimental research to avoid confounding results?

Ensuring the randomization of participants in experimental research is crucial for avoiding confounding results. Randomization helps to eliminate bias by assigning participants to different groups in a manner that is independent of any potentially confounding variables. This means that each participant has an equal chance of being assigned to any group, which helps ensure that the groups are comparable at the start of the experiment.

When participants are randomly assigned, it minimizes the influence of extraneous variables that could affect the outcomes of the study, thus enhancing the internal validity of the research. This methodological rigor is essential for attributing observed effects directly to the intervention being tested, rather than to other factors.

While equal sample size, collecting qualitative data, and having an extended observation period may contribute to the overall quality and depth of the research, they do not directly address the issue of confounding variables in the same way that randomization does. Randomization specifically targets the potential biases that could arise from uncontrolled variables, making it a foundational element in experimental design.