The Newcastle-Ottawa Scale (NOS) is a tool that is commonly used to assess the quality of observational studies, particularly case-control and cohort studies. The scale is used to evaluate the design and conduct of studies in order to assess the risk of bias.

The NOS is not typically used for qualitative studies as it is specifically designed for observational studies that are based on numerical data. Qualitative studies, on the other hand, focus on the interpretation of non-numerical data such as words, images, and video, and are typically analyzed using different methodologies such as content analysis, discourse analysis, and ethnography.

However, it's worth noting that some researchers have attempted to use the NOS for evaluating the quality of qualitative studies, but it's not a widely accepted approach and it's not as common as using other tools such as the Critical Appraisal Skills Program (CASP) or the Cochrane Risk of Bias Tool.

It's important to note that while the NOS can be adapted to evaluate qualitative studies, it would likely not be as reliable or valid as using tools specifically designed for assessing the quality of qualitative research.