Which category of evidence involves good theoretical basis but is not as robust as Category 1?

Category 1B evidence represents a level of research that is strong and relevant but may not be as rigorously validated or comprehensive as Category 1A. While it is grounded in a sound theoretical foundation, the evidence in this category may come from studies that do not have the same high-quality methodologies or larger sample sizes typically found in Category 1A studies.

Category 1B includes systematic reviews of studies with limited quality assessments or randomized control trials that demonstrate efficacy but might include some limitations, such as smaller sample sizes or less stringent controls. This contrasts with Category 1A evidence, which is derived from well-conducted randomized controlled trials or meta-analyses that provide the highest level of scientific support. Essentially, while Category 1B is reliable and still valuable in practice, it does not reach the same level of robustness as Category 1A, thus solidifying its position in the hierarchy of evidence categories.