Which of the following sources for research is considered invalid?

The choice of a popular press report as an invalid source for research is grounded in the nature of its content and intended audience. Popular press reports are typically designed for general consumption and are often characterized by sensationalism or oversimplification. They do not undergo the rigorous peer-review process that academic and scientific publications do, which is crucial for ensuring the reliability and validity of the information presented.

In contrast, juried medical journals, professional association reports, and research articles presented at national conventions undergo scrutiny by experts in the field prior to publication. This vetting process helps to ensure the credibility and accuracy of the information, making these sources much more reliable for drawing conclusions in research.

Thus, while popular press reports may provide accessible information, they often lack the depth, accuracy, and scientific rigor necessary for serious research purposes.